The Effect of UV Light and Weather on Plastics and Elastomers

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THE EFFECT OF UV LIGHT ANDWEATHER ON PLASTICS AND

ELASTOMERS

Third edition

Laurence W. McKeen

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Preface

This book is an extensive update and extension tothe second edition by the same title. The secondedition was published in 2007. Since that time, newplastic materials have been introduced. There hasbeen an expanded interest in green materialsdthosemade from renewable resources and those thatdecompose relatively quickly in the environment.There has been a turnover in ownership of theplastic-producing companies. There has been a lot ofconsolidation, which of course means discontinuedproducts. This update is much more extensive thanthe usual “next edition”.

It has been reorganized from a polymer chemistrypoint of view. Plastics of mostly similar polymertypes are grouped into 10 chapters. A brief expla-nation of the chemistry of the polymers used in theplastic films is discussed at the start of each plasticsection. This is generally consistent with the othersix books in this particular series.

An extensive introduction has been added as threechapters. The initial chapter covers polymer chem-istry, plastics and composition and how it relates tovarious general plastics properties. The secondchapter focuses on the main subject of this bookdthat of weathering of plastics. It gives an over view ofthe chemistry of weathering, including physical andchemical processes and photochemistry. There isa section on stabilizers that includes chemicalstructures and mode of operation. It also coversexposure method used to weather plastics. The thirdchapter focuses on physical, mechanical, thermal andelectrical properties of plastics. Many plastic prop-erties are discussed including how the properties aremeasured and data are presented.

Chapters 4 through 13 are like a databank thatserves as an evaluation of the performance ofhundreds of plastic materials after outdoor or ac-celerated weathering. Each of these chapters startswith a brief outline of the chemistry of the polymerin that section. There are hundreds of uniformgraphs and tables for more than 70 generic familiesof plastics used to make plastics contained in thesechapters.

The data in each chapter are generally organizedwith polymer chemistry, photo and photooxidationchemistry, a manufacturer and trade name list, anapplications and a list of end-uses followed by thedata. The tabular data in the second edition have beenverified and reformatted to take up much less spacein this edition, whereas this new edition does nothave many more pages, as there is far more infor-mation contained.

Numerous references are included. Only a limitedamount of data from the first edition has beenremoved. Removed data primarily were for dis-continued products. Product names and manufac-turers have been updated.

I am especially appreciative of the confidenceand support of my Plastics Design Library serieseditor and friend Sina Ebnesajjad. I would nothave been given the opportunity to do this workhad it not been for the support of Mathew Deans,Senior Publisher at Elsevier. His staff at Elsevier isknowledgeable and easy to work with. My wife,Linda, has been particularly supportive through thelong hours of writing and research from my homeoffice.

Laurence W. McKeen, 2013

xi

1 Introduction to Plastics and Polymers Compositions

1.1 Introduction to Plastics andPolymers

The basic component of plastic and elastomermaterials is polymer. The word polymer is derivedfrom the Greek term for “many parts”. Polymers arelarge molecules composed of many repeat unitscalled monomers that have been chemically bondedinto long chains. Since World War II, the chemicalindustry has developed a large quantity of syntheticpolymers to satisfy the materials needs for a diverserange of products, including paints, coatings, fibers,films, elastomers, and structural plastics. Literallythousands of materials can be called “plastics”,although the term today is typically reserved forpolymeric materials, excluding fibers, which can bemolded or formed into solid or semisolid objects. Asof the beginning of 2012, IDES The Plastics Web�

(http://www.ides.com) listed over 85,000 differentgrades of plastic from over 800 suppliers.

There are three introductory chapters to this book.The first chapter is a review of polymer chemistryand plastic formulation. It lays the foundation for thediscussion on weather processes, property measure-ment and all the data chapters. The second chapter isa review of weathering and ultraviolet (UV) lightexposure. This includes the various ways to exposetest plaques including natural exposures and accel-erated exposures. The physical and chemicalprocesses involved with weather and light exposureare explained. The third chapter is on plastic prop-erties. First discussed are the physical properties.Second are the mechanical properties such as tensilestrength, elongation, modulus, and tear resistance.Third are thermal properties such as melting point,glass transition temperature and melt index whichaffect use, production and processing of films.

The chapters that follow are the data chapters.Each chapter covers plastics that fall into particulartypes based on the chemistry of the polymer. Each ofthese chapters reviews the chemical structures of thepolymers used to make the plastics. In many cases,photochemistry and photodegradation reactions are

discussed. Typical stabilizers are mentioned and dataare presented in tabular and graphical forms.

The subject of this chapter includes polymeriza-tion chemistry and the different types of polymersand how they can differ from each other. Sinceplastics are rarely “neat”, reinforcement, fillers andadditives are reviewed. A basic understanding ofplastic and polymer chemistry will make thediscussion of properties of specific films easier tounderstand and it also provides a basis for theintroduction of the plastic families in later chapters.This chapter is taken from The Effect of Temperatureand Other Factors on Plastics1 and PermeabilityProperties of Plastics and Elastomers,2 but it hasbeen rewritten, expanded and refocused on polymersas they relate to plastics that may be exposured tovarious weathering processes.

1.1.1 Polymerization

Polymerization is the process of chemicallybonding monomer building blocks to form largemolecules. Commercial polymer molecules areusually thousands of repeat units long. Polymeriza-tion can proceed by one of several methods. The twomost common methods are called addition andcondensation polymerization.

1.1.1.1 Addition Polymerization

In addition polymerization (sometimes calledchain-growth polymerization), a chain reaction addsnew monomer units to the growing polymer mole-cule one at a time through double or triple bonds inthe monomer. The polymerization process takesplace in three distinct steps:

1. Chain initiation: usually by means of aninitiator which starts the polymerizationprocess. The reactive initiation molecule canbe a radical (free radical polymerization),cation (cationic polymerization), anion (anionic

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polymerization) or/and organometalliccomplex (coordination polymerization).

2. Chain propagation: a monomer adds ontochain and each new monomer unit creates anactive site for the next attachment. The netresult is shown in Fig. 1.1.

3. Chain termination: the radical, cation or anionis “neutralized” stopping the chainpropagation.

Many of the plastics discussed in later chapters ofthis book are formed in this manner. Some of theplastics made by addition polymerization includepolyethylene, polyvinyl chloride (PVC), acrylics,polystyrene, and polyoxymethylene (acetal).

1.1.2 CondensationPolymerization

The other common method is condensation poly-merization (also called step-growth polymerization)in which the reaction between monomer units and thegrowing polymer chain end group releases a smallmolecule, often water, as shown in Fig. 1.2. Themonomers in this case have two reactive groups. Thisreversible reaction will reach equilibrium and haltunless this small molecular by-product is removed.Polyesters and polyamides are among the plasticsmade by this process.Understanding the polymerization process used to

make a particular plastic gives insight into the nature ofthe plastic. For example, plastics made via condensa-tion polymerization, in which water is released, candegrade when exposed to water at high temperature.

Polyesters such as polyethylene terephthalate (PET)can degrade by a process called hydrolysis whenexposed to acidic, basic or even some neutral envi-ronments severing the polymer chains. The polymer’sproperties are degraded as a result.

1.2 Copolymers

A copolymer is a polymer formed when two (ormore) different types of monomers are linked in thesame polymer chain, as opposed to a homopolymerwhere only one monomer is used. If exactly threemonomers are used, it is called a terpolymer.Monomers are only occasionally symmetric; the

molecular arrangement is the same no matter whichend of the monomer molecule you are looking at.The arrangement of the monomers in a copolymercan be head to tail, head to head, or tail to tail. Sincea copolymer consists of at least two types ofrepeating units, copolymers can be classified basedon how these units are arranged along the chain.These classifications include

� Alternating copolymer

� Random copolymer (statistical copolymer)

� Block copolymer

� Graft copolymer

When the two monomers are arranged in analternating fashion, the polymer is called, of course,an alternating copolymer.

Figure 1.1 Additionpolymerization.

Figure 1.2 Condensation polymerization.

Alternating copolymer

2 THE EFFECT OF UV LIGHT AND WEATHER ON PLASTICS AND ELASTOMERS

In the following examples, A and B are differentmonomers. Keep in mind that A and B do not have tobe present in a 1:1 ratio. In a random copolymer, thetwo monomers may follow in any order.

In a block copolymer, all of one type ofmonomer isgrouped together, and all of the second monomer aregrouped together. A block copolymer can be thoughtof as two homopolymers joined together at the ends.

A polymer that consists of large grouped blocks ofeach of the monomers is also considered a blockcopolymer.

When chains of a polymer made of monomer Bare connected onto a polymer chain of monomer A,we have a graft copolymer.

High-impact polystyrene is a graft copolymer. It isa polystyrene backbone with chains of polybutadienegrafted onto the backbone. Polystyrene gives thematerial strength, but the rubbery polybutadienechains give it resilience to make it less brittle.

1.3 Linear, Branched and Cross-Linked Polymers

Some polymers are linear, a long chain of connectedmonomers. Polyethylene, PVC, Nylon 66 and poly-methyl methacrylate are some linear commercialexamples found in this book. Branched polymers canbevisualized as a linear polymerwith side chains of thesame polymer attached to the main chain. While thebranches may in turn be branched, they do not connectto another polymer chain. The ends of the branches arenot connected to anything. Special types of branchedpolymers include star polymers, combpolymers, brushpolymers, dendronized polymers,3 ladders, and den-drimers. Cross-linked polymer, sometimes callednetwork polymer, is one in which different chains areconnected. Essentially the branches are connected todifferent polymer chains on the ends. These threepolymer structures are shown in Fig. 1.3.

1.4 Polarity

A molecule is two or more atoms joined bya covalent bond. Basically the positively chargedatom nuclei share the negatively charged electrons.However, if the atoms are different they may notshare the electrons equally. The electrons will bedenser around one of the atoms. This would makethat end more negatively charged than the other endand creates a negative and a positive pole (a dipole).Such a bond is said to be a polar bond and themolecule is polar and has a dipole moment. Ameasure of how much an atom attracts electrons iselectronegativity. The electronegativity of commonatoms in the polymers follows:

F > O > Cl and N > Br > C and H

Figure 1.3 (a) Linear, (b) branched and (c) cross-linked polymers.

Random copolymer

Block copolymer

Block copolymer

Branched/Grafted copolymer

1: INTRODUCTION TO PLASTICS AND POLYMERS COMPOSITIONS 3

The polarity of a molecule affects the attractionbetween molecular chains, which affects the struc-ture of the polymer and the attraction of polarmolecules, so one would expect polarity to affectsolubility, which affects permeability.How does one predict molecular polarity? When

there are no polar bonds in a molecule, there is nopermanent charge difference between one part of themolecule and another so the molecule is nonpolar.For example, the Cl2 molecule has no polar bondsbecause the electron charge is identical on bothatoms. It is therefore a nonpolar molecule. The CeCand CeH bonds in hydrocarbon molecules, such asethane, C2H6, are not significantly polar, so hydro-carbons are nonpolar molecular substances andhydrocarbon polymers like polyethylene or poly-propylene are also nonpolar.A molecule can possess polar bonds and still be

nonpolar, however. If the polar bonds are evenly (orsymmetrically) distributed, the bond dipoles canceland do not create a molecular dipole. For example,the three bonds in a molecule of CCl4 are signifi-cantly polar, but they are symmetrically arrangedaround the central carbon atom. No side of themolecule has more negative or positive charge thanthe other side, and so the molecule is nonpolar(Table 1.1).Generally, polar polymers are more permeable to

water than nonpolar polymers. Figure 1.4 showsa qualitative ranking of some polymers polarities.

1.5 Unsaturation

Up to this point in the discussion of polymerchemistry, the atom to atom structure has not beendiscussed. The covalent bonds between atoms ina polymer can be single, double, triple bonds or evenrings. The presence of bonds higher than singlebonds generally makes the polymer molecule stifferand reduces rotation along the polymer chain, and

that can affect its properties. It is easier to discussmolecules first and then extend that discussion topolymers. Saturated molecules only contain singlebonds with no rings.Often when talking about molecular unsaturation,

the degree of unsaturation (DoU) is noted. Tocalculate the DoU, if the molecular formula is given,it can be calculated using Eqn (1.1):

DoU ¼ 2C þ 2þ N � X � H

2(1.1)

� C¼ number of carbons

� N¼ number of nitrogens

Table 1.1 Dipole Moments in Some Small Molecules

Molecule Dipole Moment Molecule Dipole Moment Molecule Dipole Moment

H2 0 HF 1.75 CH4 0.0

O2 0 H2O 1.84 CH3Cl 1.86

N2 0 NH3 1.46 CCl4 0

Cl2 0 NF3 0.24 CO2 0

Br2 0 BF3 0 e e

High polarity Nylon 6/6 Nylon 6 Polyethylene terephthalate (PET) Cellulose acetate Nitrile Rubber (NBR) (50% acrylonitrile) Polyurethane Nitrocellulose Epoxy Polycarbonate (PC) Polymethyl methacrylate (PMMA) Polyvinyl acetate Nitrile Rubber (NBR) (30% acrylonitrile) Acrylate elastomers Polyvinyl butyral Polyepichlorohydrin Cellulose acetate butyrate Polystyrene Polyvinyl alcohol Polychloroprene Polyethylene Nitrile Rubber (NBR) (20% acrylonitrile) Chlorinated polyethylene Styrene-Butadiene Rubber (SBR) Polybutadiene Natural rubber Halogenated butyl Polypropylene Ethylene Propylene Diene Monomer Rubber (EPDM)Butyl rubber Perfluorinated polymers Low Polarity Silicone

Figure 1.4 Qualitative ranking of polymer polarities.


� X¼ number of halogens (F, Cl, Br, I)

� H¼ number of hydrogens

� Oxygen and sulfur are not included in the formulabecause saturation is unaffected by theseelements.

Examples:

Ethylene: C2H4

DoU ¼ 2C þ 2þ N � X � H

2

¼ 2*2þ 2þ 0� 0� 4

2¼ 1

(1.2)

Benzene: C6H6

DoU ¼ 2C þ 2þ N � X � H

2

¼ 2*6þ 2þ 0� 0� 6

2¼ 4

(1.3)

When polymers are used, the formula shown isoften the repeating unit. This will often have twobonds that are shown to which the repeating unit issupposed to attach. If applying a DoU formula to therepeating unit, one would remove the “þ2” in theformula.

Examples:

Polyethylene ðPEÞ: eðCH2eCH2ÞneDoU ¼ 2C þ N � X � H

2

¼ 2*2þ 0� 0� 4

2¼ 0

(1.4)

Polyphenylene sulfone ðPPSÞ: eðC6H4eSÞneDoU ¼ 2C þ N � X � H

2

¼ 2*6þ 0� 0� 4

2¼ 4

(1.5)

1.6 Steric Hindrance

As described earlier in this chapter, polymers arelong chains of atoms linked together. They may beflexible and bendable. To explain this one may visu-alize them as ball-and-stick model. In chemistry, theball-and-stick model is a molecular model ofa chemical substance which aims to display both thethree-dimensional position of the atoms and the bonds

between them. The atoms are typically represented byspheres, connected by rods which represent the bonds.Double and triple bonds are usually represented bytwo and three curved rods, respectively. The chemicalelement of each atom is often indicated by thesphere’s color. The top of Fig. 1.5 shows a drawing ofa ball-and-stick model of a molecule. Figure 1.5 alsoindicates that there is free rotation around the singlebonds. If there was a double or triple bond, therewould not be any rotation possible around thosebonds. Similarly, ring structures, while they mightflex a little bit, inhibit rotation. In some cases such asthat shown in the bottom of Fig. 1.5, large atoms orbulky side groups might bump into each other as themolecule rotates around single bonds. This is calledsterically hindered or steric hindrance. Hindered orinhibited rotation stiffens the polymer molecule anddramatically affects its physical properties.

1.7 Isomers

Isomers (from Greek isomeres; isos¼ “equal”,meros¼ “part”) are compounds with the samemolecular formula but a different arrangement of theatoms in space. There are many kinds of isomers andthe properties can differ widely or almost not at all.

1.7.1 Structural Isomers

Structural isomers have the atoms arranged ina completely different order as shown in Fig. 1.6.Here, both polymer repeating groups have the sameformula, eC4H8e, but the atoms are arranged

Figure 1.5 Steric hindrance shown with a ball-and-stick molecular model.


differently. The properties of structural isomers maybe very different from each other.Often the repeating group in a polymer has exactly

the same formula, but the repeating group is flippedover as shown in Fig. 1.7. If one views the repeatinggroup as having a head and a tail, then the differentways to connect neighboring repeating units isheadetail, headehead and tailetail.

1.7.2 Geometric Isomers

When there is a carbonecarbon double bond inamolecule, theremight also be twoways to arrange thegroups attached to the double bonds. This is best seenin side-by-side structures such as shown in Fig. 1.8.These are called geometric isomers that owe their

existence to hindered rotation about double bonds. Ifthe substituents are on the same side of the doublebond, then the isomer is referred to as cis (Latin: onthis side). If the substituents are on the opposite sideof the double bond, then the isomer is referred to astrans (Latin: across).

1.7.3 Stereoisomers:Syndiotactic, Isotactic, Atactic

Stereoisomerism occurs when two or more mole-cules have identical molecular formula and the same

structural formula (i.e. the atoms are arranged in thesame order). However, they differ in their two- orthree-dimensional spatial arrangements of theirbonds, which mean different spatial arrangement ofthe atoms, even though they are bonded in the sameorder. This may best be understood by an example.Polypropylenes all have the same simplified

structural polymer formula of polypropene as shownin Fig. 1.9.However, there are subtle differences in the ways

of drawing this structure. Figure 1.10 shows a longerstructure of polypropene, one that also shows somethree-dimensional structure. This structure showshow some bonds, (the dotted lines) are behind theplane of the paper and others stick out of the paper(the ones on the ends of the little triangular wedges).In this structure some of the CH3 groups are abovethe paper plane and others are behind the paperplane. This is called atactic polypropene.

Figure 1.7 Head-to-tail isomers.4

Figure 1.8 (a) Cis- and (b) trans- isomers.

Figure 1.9 The structure of polypropene.

Figure 1.6 Structural isomers.


Atactic polypropene has at random about 50%of hydrogen/methyl groups in front/back ofCeCeC chain viewing plane. This form of pol-ypropene is amorphous (noncrystalline, discussedin Section 1.9.3) and has an irregular structuredue to the random arrangement of the methylgroups attached to the main carbonecarbonchain. It tends to be softer and more flexible thanthe other forms (described below) and is used forroofing materials, sealants and other weatherproofcoatings.

Isotactic polypropene has all the methyl groups infront of CeCeC chain viewing plane and all the H’sat the back as shown in Fig. 1.11. This stereoregularstructure maximizes the moleculeemolecule contactthus increasing the intermolecular forces comparedto the atactic form. This regular structure is muchstronger (than the atactic form above) and is used insheet and film form for packaging and carpet fibers.

Syndiotactic polypropene has a regular alternationof 50% of hydrogen/methyl groups in the front/backof the CeCeC chain viewing plane as shown inFig. 1.12. Its properties are similar to isotactic pol-ypropene rather than the atactic form, i.e. the regularpolymer structure produces stronger intermolecularforces and a more crystalline form than the atacticpolypropene.

1.8 Inter- and IntramolecularAttractions in Polymers

The attractive forces between different polymerchains or segments within polymer chains play

a large part in determining a polymer’s properties.As mentioned in Section 1.4, atoms can havepolarity or dipole moments. Since negativecharges are attracted to the opposite positivecharges and are repelled by like charges, it ispossible to generate attractions that lead to certainstructures.

1.8.1 Hydrogen Bonding

One of the strongest dipole interactions is theattraction of some oxygen atoms to hydrogenatoms, even though they are covalently bonded toother atoms. This is called hydrogen bonding anda schematic of such bonding is shown in Fig. 1.13.The NeH bond provides a dipole when thehydrogen has a slightly positive charge and thenitrogen has a slight negative charge. The carbonylgroup, C]O, likewise is a dipole, where theoxygen has slight negative charge and the carbon isslightly positive. When polymer chains line up,these hydrogen bonds are formed (indicated by thewide gray bars in the figure), bonds that are farweaker than the covalent bonds but bonds ofsignificant strength nonetheless.

Other side groups on the chain polymer can lendthe polymer to hydrogen bond between its ownchains. These stronger forces typically result inhigher tensile strength and higher crystalline meltingpoints. Polyesters have dipoleedipole bondingbetween the oxygen atoms in C]O groups and thehydrogen atoms in HeC groups. Dipole bonding isnot as strong as hydrogen bonding.

Figure 1.10 The structure ofatactic polypropene.

Figure 1.11 The structure ofisotactic polypropene.

Figure 1.12 The structure of syn-diotactic polypropene.


1.8.2 Van der Waals Forces

Many polymers, such as polyethylene, have nopermanent dipole. However, attractive forcesbetween polyethylene chains arise from weak forcescalled van der Waals forces. Van der Waals forces aremuch weaker than chemical bonds, and randomthermal motion around room temperature can usuallyovercome or disrupt them.Molecules can be thought of as being surrounded

by a cloud of negative electrons. But the electrons aremobile, and at any one instant, they might findthemselves toward one end of the molecule, makingthat end slightly negative (d�). The other end will bemomentarily short of electrons and so becomes dþ.Basically, temporary fluctuating dipoles are present inall molecules and the forces due to these dipoles arethe basis for van der Waals attraction. van der Waalsforces are quite weak, however, so polyethylene canhave a lower melting temperature compared to otherpolymers that have hydrogen bonding.

1.8.3 Chain Entanglement

Polymer molecules are long chains, which canbecome entangled with one another, much like a bowlof spaghetti. Along with intermolecular forces, chainentanglement is an important factor contributing tothe physical properties of polymers. The difficulty inuntangling their chains makes polymers and theplastic made from them strong and resilient.

1.9 General Classifications

Besides the chemical structures of the polymers inthe plastics, there are several other characterizations

that are important including molecular weight,thermoplastics vs thermosets, and crystallinity.

1.9.1 Molecular Weight

A polymer’s molecular weight is the sum of theatomic weights of individual atoms that comprisea molecule. It indicates the average length of thebulk resin’s polymer chains. All polymer moleculesof a particular grade do not have exactly samemolecular weight. There is a range or distribution ofmolecular weights. There are two important butdifferent ways to calculate molecular weight. Themost important one is called the number-averagemolecular weight, Mn. For all “i” molecules ina sample, the number-average molecular weight iscalculated using Eqn (1.6).

Mn ¼P

iNiMi

P

iNi

(1.6)

wherei is the number of polymer moleculesNi is the number of molecules that have molecular

weight Mi

Theweight average molecular weight is a differentcalculation as in Eqn (1.7)

Mw ¼P

iNiM

2i

P

iNi

(1.7)

Figure 1.14 shows a molecular weight distributionchart with the two different molecular weightmeasures noted on it. The ratio Mw/Mn is calledthe molar-mass dispersity index5 (often called

Figure 1.13 Schematic of hydrogenbonding in a pair of polymer chains.


polydispersity (PDI)).5 If all polymer chains areexactly the same, then the number-average andweight-average molecular weights are exactly thesame and the PDI is 1. The larger the molar-massdispersity index, the wider is the molecular weightdistribution. The molecular weight range can affectmany properties of plastic materials.

Another common means of expressing the lengthof a polymer chain is the degree of polymerization;this quantifies the average number of monomersincorporated into the polymer chain. The averagemolecular weight can be determined by severalmeans, but this subject is beyond the scope of thisbook. Low-molecular-weight polyethylene chainshave backbones as small as 1000 carbon atoms long.Ultrahigh-molecular-weight polyethylene chains canhave 500,000 carbon atoms along their length. Manyplastics are available in a variety of chain lengths ordifferent molecular weight grades. These resins canalso be classified indirectly by a viscosity value,rather than molecular weight. Within a resin family,such as polycarbonate, higher molecular weightgrades have higher melt viscosities. For example, inthe viscosity test for polycarbonate, the melt flowrate ranges from approximately 4 g/10 min for thehighest molecular weight, standard grades to morethan 60 g/10 min for lowest molecular weight, high-flow, specialty grades.

Selecting the correct molecular weight for aninjection-molding application generally involvesa balance between filling ease and material perfor-mance. If the application has thin-walled sections,a lower molecular weight/lower viscosity gradeoffers better flow. For normal wall thicknesses, theseresins also offer faster mold cycle times and fewermolded-in stresses. The stiffer flowing, high-molec-ular-weight resins offer the ultimate materialperformance, being tougher and more resistant tochemical and environmental attack.

Molecular weight of the polymers that are used inengineering plastics affects many of the plasticsproperties. While it is not always known exactlywhat the molecular weights are, as mentioned above,higher flowing plastics of a given series of productsgenerally are lower molecular weight polymers.Molecular weight can also affect the permeationproperties as shown in Fig. 1.15.

1.9.2 Thermosets vsThermoplastics

A plastic or elastomer falls into one of two broadcategories depending on its response to heat: ther-moplastics or thermosets. Thermoplastics soften andmelt when heated and harden when cooled. Becauseof this behavior, these resins can be injection mol-ded, extruded or formed via other molding

Figure 1.14 Hypothetical molecular weight distribu-tion plot showing number- and weight-averagemolecular weights.

Figure 1.15 Water permeation of ethyleneevinylalcohol copolymer vs polymer molecular weight.6


techniques. This behavior also allows productionscrap runners and trimmings to be reground andreused. Thermoplastics can often be recycled.As described earlier, unlike thermoplastics, ther-

mosets react chemically to form cross-links that limitchain movement. This network of polymer chainstends to degrade, rather than soften, when exposed toexcessive heat. Until recently, thermosets could notbe remelted and reused after initial curing. Recentadvances in recycling have provided new methodsfor remelting and reusing thermoset materials.

1.9.3 Crystalline vs Amorphous

Thermoplastics are further classified on the basis oftheir crystallinity, or the degree of order within thepolymer’s overall structure.As a crystalline resin coolsfrom themelt, polymer chains fold or align into highlyordered crystalline structures as shown in Fig. 1.16.Some plastics can be completely amorphous or

crystalline. Often, plastics specifications will reportwhat percentage of it is crystalline as a percentage,such as 73% crystallinity. Generally, polymer chainswith bulky side groups cannot form crystallineregions. The degree of crystallinity depends on boththe polymer and the processing technique. Somepolymers such as polyethylene crystallize quicklyand reach high levels of crystallinity. Others, such asPET polyester, require slow cooling to crystallize. Ifcooled quickly, PET polyester remains amorphous inthe final product.Crystalline and amorphous plastics have several

characteristic differences. Amorphous polymers do

not have a sharp melting point, but do have what iscalled a glass transition temperature, Tg. Glasstransition temperature is the temperature at whicha polymer changes from hard and brittle to soft andpliable. The force to generate flow in amorphousmaterials diminishes slowly as the temperaturerises above the glass transition temperature. Incrystalline resins, the force requirements diminishquickly as the material is heated above its crys-talline melt temperature. Because of these easierflow characteristics, crystalline resins have anadvantage in filling thin-walled sections of a mold.Crystalline resins generally have superior chemicalresistance, greater stability at elevated temperaturesand better creep resistance. Amorphous plasticstypically have better impact strength, less moldshrinkage, and less final part warping than crys-talline materials. Higher crystallinity usually leadsto lower permeation rates. End-use requirementsusually dictate whether an amorphous or crystallineresin is preferred.

1.10 Plastic Compositions

Plastics are usually formulated products meaningthat they are not always neat polymers. They may beblends of polymers and may have many additivesused to tailor performance properties.Polymers can often be blended. Occasionally,

blended polymers have properties that exceed thoseof either of the constituents. For instance, blends ofpolycarbonate resin and PET polyester, originallycreated to improve the chemical resistance of poly-carbonate, actually have fatigue resistance and low-temperature impact resistance superior to either ofthe individual polymers.Sometimes a material is needed that has some

properties of one polymer and some of the propertiesof another. Instead of going back into the laboratoryand trying to synthesize a brand new polymer with allthe required properties, two polymers can be meltedtogether to form a blend, which will hopefully havesome properties of both.Two polymers that do actually mix well are

polystyrene and polyphenylene oxide. Other exam-ples of polymer pairs that will blend are

� PET with polybutylene terephthalate

� Polymethyl methacrylate with polyvinylidenefluoride

Figure 1.16 Many plastics have crystalline andamorphous regions.


Phase-separated mixtures are obtained when onetries to mix most polymers. But strangely enough,the phase-separated materials often turn out to berather useful. They are called immiscible blends.

Polystyrene and polybutadiene are immiscible.When polystyrene is mixed with a small amount ofpolybutadiene, the two polymers do not blend. Thepolybutadiene separates from the polystyrene intolittle spherical blobs. If this mixture is viewed undera high-power microscope something that looks likethe picture in Fig. 1.17 would be seen.

Multiphase polymer blends are of major economicimportance in the polymer industry. The mostcommon examples involve the impact modificationof a thermoplastic by the microdispersion of a rubberinto a brittle polymer matrix. Most commercialblends consist of two polymers combined with smallamounts of a third, compatibilizing polymer, typi-cally a block or graft copolymer.

Multiphase polymer blends are easier to processthan a single polymer with similar properties. Thepossible blends from a given set of polymers offermany more physical properties than do the individualpolymers. This approach has shown some successbut becomes cumbersome when more than a fewcomponents are involved.

Blending two or more polymers offers yet anothermethod of tailoring resins to a specific application.Because blends are only physical mixtures, theresulting polymer usually has physical andmechanical properties that lie somewhere betweenthe values of its constituent materials. For instance,an automotive bumper made from a blend of poly-carbonate resin and thermoplastic polyurethaneelastomer gains rigidity from the polycarbonate resin

and retains most of the flexibility and paintability ofthe polyurethane elastomer. For business machinehousings, a blend of polycarbonate and acrylonitrile-butadiene-styrene copolymer resins offers theenhanced performance of polycarbonate flameretardance and UV stability at a lower cost.

Additional information on the subject of polymerblends is available in the literature.7e9

The properties of neat polymers are often not idealfor production or end use. When this is the case,materials are added to the polymer to improve theperformance shortfall. The additives can improve theprocessing and performance of the plastic. Forwhatever reason the additive is used, it can affect thepermeation, diffusion and solubility properties.

Additives encompass a wide range of substancesthat aid processing or add value to the finalproduct.10,11 Found in virtually all plastics, mostadditives are incorporated into a resin family by thesupplier as part of a proprietary package. Forexample, you can choose standard polycarbonateresin grades with additives for improved internalmold release, UV stabilization, and flame retardanceor nylon grades with additives to improve impactperformance.

Additives often determine the success or failure ofa resin or system in a particular application. Manycommon additives are discussed in the followingsections. Except for reinforcement fillers, mostadditives are added in very small amounts.

1.10.1 Fillers, Reinforcement, andComposites

Reinforcing fillers can be added in large amounts.Some plastics may contain as much as 60% rein-forcing fillers. Often, fibrous materials, such as glassor carbon fibers, are added to resins to create rein-forced grades with enhanced properties. Forexample, adding 30% short glass fibers by weight tonylon 6 improves creep resistance and increasesstiffness by 300%. These glass-reinforced plasticsusually suffer some loss of impact strength andultimate elongation and are more prone to warpingbecause of the relatively large difference in moldshrinkage between the flow and cross-flowdirections.

Plastics with nonfibrous fillers such as glassspheres or mineral powders generally exhibit higherstiffness characteristics than unfilled resins, but not

Figure 1.17 Immiscible blend of polystyrene andpolybutadiene.


as high as fiber-reinforced grades. Resins withparticulate fillers are less likely to warp and showa decrease in mold shrinkage. Particulate fillerstypically reduce shrinkage by a percentage roughlyequal to the volume percentage of filler in the poly-mer, an advantage in tight tolerance molding.Often, reinforced plastics are called composites.

Often, the plastic material containing the reinforce-ment is referred to as the matrix. One can envisiona number of ways by which different reinforcingmaterials might be arranged in a composite. Many ofthese arrangements are shown in Fig. 1.18.Particulates, in the form of pigments, to impart

color may be added. Occasionally, particulate, calledextender, is added to reduce the amount of relativelyexpensive polymer used, which reduces the overallcost.Platelet additives may impart color and luster,

metallic appearance or a pearlescent effect, but theyalso can strongly affect permeation properties. Mostof these additives have little or no permeation by

themselves, so when a film contains particulateadditives, the permeating molecule must followa path around the particulate additive as shown inFig. 1.19. This is often called a tortuous path effect.

1.10.2 Combustion Modifiers,Fire, Flame Retardants andSmoke Suppressants

Combustion modifiers are added to polymers tohelp retard the resulting parts from burning. Gener-ally required for electrical and medical housingapplications, combustion modifiers and theiramounts vary with the inherent flammability of thebase polymer. Polymers designed for these applica-tions often are rated using an Underwriters Labora-tories rating system. These ratings should be used forcomparison purposes only, as they may not accu-rately represent the hazard present under actual fireconditions.

Figure 1.18 Several types of compositematerials.


1.10.3 Release Agents

External release agents are lubricants, liquids orpowders, which coat a mold cavity to facilitate partremoval. Internal release agents can accomplish thesame purpose. The identity of the release agent israrely disclosed, but frequently, they are fine fluo-ropolymer powders, called micropowders, siliconeresins or waxes.

1.10.4 Slip Additives/InternalLubricants

When plastics (particularly films) slide over eachother, there is a resistance that is quantified in termsof the coefficient of friction (COF). Films with highCOF tend to stick together instead of sliding over oneanother. Sticking makes the handling, use andconversion of films difficult. To overcome sticking,slip agents are added.

Slip additives can be divided into two:migrating andnonmigrating types. Migrating slip additives are themost common class and they are used above theirsolubility limit in the polymer. These types of additivesare molecules that have two distinct parts, typically

pictured as a head and tail as shown in Fig. 1.7.One partof the molecule, usually the head, is designed to besoluble in the polymer (particularly when it is moltenduring processing) making up the plastic. The otherpart, the tail, is insoluble. As the plastic cools andsolidifies fromitsmolten state, thesemoleculesmigrateto the surface, where the insoluble end “sticks up”reducing the COF. This process is shown in Fig. 1.20.These additives are typically fatty acid amides.

There are migrating slip additives that do not havethis two-part structure. One additive is per-fluoropolyether synthetic oil marketed by DuPont�under the trademark Fluoroguard�, which is aninternal lubricant that imparts improved wear andlow friction properties. Silicone fluids, such as thosemade by Dow Corning, can also act as a boundarylubricant. Both these materials may migrate to thesurface of the plastic over time.

The following are some common nonmigratingslip additives:

� Polytetrafluoroethylene in micropowder formimparts the lowest COF of any internal lubricant.Manufacturers and suppliers are many includingDuPont� Zonyl� and 3M Dyneon�.

Figure 1.19 Tortuous path of permeantmolecule through a platelet particulatecontaining film.

Figure 1.20 Mode of action ofa typical migrating slip additive.


� Molybdenum disulfide, commonly called “moly”is a solid lubricant often used in bearingapplications.

� Graphite is a solid lubricant used like molyb-denum disulfide.

1.10.5 Antiblock Additives

Blocking is a surface affect between adjacentfilm layers that stick to one another. Blocking isquantified by the force needed to separate twofilm layers under controlled conditions. Twosituations where blocking is an issue are theopening of blown film tubes after extrusion andfilm layer separation after packing and storage.Antiblock additives are used to overcome theseissues.Antiblock additives can be divided into two

classes: inorganic and organic. Chemically inert,inorganic antiblock additives migrate to the filmsurface and partially stick out of the surface to createa microroughness of the film surface. Figure 1.21illustrates this principle.The detailed mechanism of how organic

antiblock additives work is not yet understood. It isthought that a barrier layer is formed on the plasticfilm surface, thus inhibiting the two adjacentplastic film layers’ adhesion. Their usage islimited. Organic antiblock additives were partiallydiscussed above and will not be further mentionedhere.

1.10.6 Catalysts

Catalysts, substances that initiate or change therate of a chemical reaction, do not undergoa permanent change in composition or become partof the molecular structure of the final product.Occasionally used to describe a setting agent, hard-ener, curing agent, promoter, etc., they are added inminute quantities, typically less than 1%.

1.10.7 Impact Modifiers andTougheners

Many plastics do not have sufficient impactresistance for the use for which they are intended.Rather than change to a different type of plastic, theycan be impact modified in order to fulfill theperformance in use requirements. Addition ofmodifiers called impact modifiers or tougheners cansignificantly improve impact resistance. This is oneof the most important additives. There are manysuppliers and chemical types of these modifiers.General-purpose impact modification is a very low

level of impact modification. It improves room-temperature impact strength but does not take intoaccount any requirement for low-temperature (below0 �C) impact strength. For most of these types ofapplications only low levels of impact modifier willbe required (<10%).Low-temperature impact strength is required for

applications that require a certain level of low-temperature flexibility and resistance to break. Thisis, for example, the case for many applications in theappliance area. For this purpose, modifier levelsbetween 5% and 15% of mostly reactive modifierswill be necessary. Reactive modifiers can bondchemically to the base polymer.Super tough impact strength may be required for

applications that should not lead to a failure of the parteven if hit at low temperatures (�30 to�40 �C) underhigh speed. This requirement can only be fulfilledwith high levels (20e25%) of reactive impact modi-fierwith low glass transition temperature (seeChapter3.4.5 for discussion of glass transition temperature).

1.10.8 UV/Radiation Stabilizers

Stabilizers like antioxidants and free radial scav-engers can prevent degradation and cross-linking.This subject is discussed in detail in Chapter 2.

Figure 1.21 Antiblock additives maintain filmseparation.


1.10.9 Optical Brighteners

Many polymers have a slight yellowish color. Theycan be modified to appear whiter and brighter byincreasing the reflected bluish light (in the range of400e600 nm). Oneway to accomplish this is by usingan additive that absorbs in the UV range but reemitsthe energy at higher wavelength. This effect is calledfluorescence and these types of additives are calledoptical brighteners or fluorescent whitening agents.This subject is discussed in detail in Chapter 2.

1.10.10 Plasticizers

Plasticizers are added to help maintain flexibilityin a plastic. Various phthalates are commonly usedfor this purpose. Since they are small molecules, theymay extract or leach out of the plastic causing loss offlexibility with time. Just as deliberately added smallmolecules may leach out, small molecules from theenvironment may be absorbed by the plastic and actlike a plasticizer. The absorption of water by nylons(polyamides) is an example. Plasticizers increase thespace between the polymers.

1.10.11 Pigments, Extenders,Dyes, and Mica

Pigments are added to give plastic color, but theymay also affect the physical properties. Extenders areusually cheap materials added to reduce the cost ofplastic resins. Dyes are colorants chemicallydifferent from pigments. Mica is a special pigmentadded to impact sparkle or metallic appearance.Titanium dioxide and carbon black are two importantpigments that merit further discussion.

1.10.11.1 Titanium Dioxide

Titanium dioxide (TiO2) is one of the mostimportant pigment. It is widely used because it effi-ciently scatters visible and absorbs UV light, therebyimparting whiteness, brightness and opacity whenincorporated into a plastic. Titanium dioxide iscommercially available in two crystal structur-esdanatase and rutile. Rutile TiO2 pigments arepreferred because they scatter light more efficiently,are more stable and are more durable than anatasepigments. Chalk resistance, retention of color (tintedpaints) and gloss, and resistance to discoloration by

mildew and dirt collection can be influenced by TiO2

grade selection.Few, if any, commercial grades of titanium dioxide

are pure TiO2. Most have inorganic and, in somecases, organic treatments deposited on the surfacesof the TiO2 particles by precipitation, by mechanicalblending, or via other routes. Unlike coloredpigments that primarily provide opacity by absorbingvisible light, titanium dioxide and other whitepigments also provide opacity by scattering light.

1.10.11.2 Carbon Black

Carbon black describes a group of industrialcarbons created through the partial combustion or thethermal decomposition of hydrocarbons. Carbonblack is unique in that it possesses the smallestparticle size and highest oil absorption among thecommercially available pigments for plastics. Thesecharacteristics lead to carbon black’s excellent colorstrength, cost-effectiveness, and UV performanceand place it as the most widely used black pigmentfor thermoplastic applications.

1.10.12 Coupling Agents

The purpose of adding fillers is to lower the cost ofthe polymer, make it tougher or stiffer or make itflame retardant so that it does not burn when it isignited. Often the addition of the filler will reduce theelongation at break, the flexibility and in many casesthe toughness of the polymer because the fillers areadded at very high levels. One reason for thedegradation of properties is that the fillers in mostcases are not compatible with the polymers. Theaddition of coupling agents can improve thecompatibility of the filler with the polymer. Asa result, the polymer will like the filler more, thefiller will adhere better to the polymer matrix and theproperties of the final mixture (e.g. elongation,flexibility) will be enhanced.

1.10.13 Thermal Stabilizers

One of the limiting factors in the use of plastics athigh temperatures is their tendency to not onlybecome softer but also to thermally degrade.Thermal degradation can present an upper limit tothe service temperature of plastics. Thermal degra-dation can occur at temperatures much lower than


those at which mechanical failure is likely to occur.Plastics can be protected from thermal degradationby incorporating stabilizers into them. Stabilizerscan work in a variety of ways but discussion of thesesmechanisms are beyond the purpose of this book.

1.10.14 Antistats

Antistatic additives are capable of modifyingproperties of plastics in such a way that they becomeantistatic, conductive, and/or improve electromag-netic interference shielding. Carbon fibers, conduc-tive carbon powders, and other electricallyconductive materials are used for this purpose.When two (organic) substrates rub against each

other, electrostatic charges can build up. This isknown as tribocharging. Electrostatic charges canimpact plastic parts in several ways; one of the mostannoying being the attraction of dust particles. Oneway to counter this effect is to use antistats (or anti-static additives). This effect is principally a surfaceeffect, although one potential countermeasure(conductive fillers) converts it into a bulk effect.Tools that decrease electrostatic charges and hence

increase the conductivity of an organic substrate canbe classified as

� External antistat (surface effect)

� Conductive filler (bulk and surface effect)

� Internal antistat (surface effect).

An external antistat is applied via a carriermedium to the surface of the plastic part. The sameconsiderations and limitations apply as with non-migrating slip additives. Conductive filler is incor-porated into the organic substrates and builds upa conductive network on a molecular level. Whileboth approaches are used in organic substrates, theyare not the most common.An internal antistat is compounded into the

organic substrate and migrates to the plastic partsurface. The same principle considerations apply asfor migrating slip additives (Fig. 1.20).The need to protect sensitive electronic compo-

nents and computer boards from electrostatic

discharge during handling, shipping, and assemblyprovided the driving force for the development ofa different class of antistatic packaging materials.These are sophisticated laminates with very thinmetalized films.There are other additives used in plastics, but the

ones discussed above are the most common.

1.11 Summary

The basis of all plastics is polymers. Most of thischapter did not go into the chemical structures of allthe polymers. The data chapters start from Chapter 4and the chemical structures of the polymers arediscussed in the appropriate sections.

References

1. McKeen LW. The effect of temperature and otherfactors on plastics. 2nd ed. William Andrew;2008.

2. McKeen LW. Permeability properties of plasticsand elastomers. 3rd ed. Elsevier; 2011.

3. http://en.wikipedia.org/wiki/Dendronized_polymers.4. This is a file from the Wikimedia Commons

which is a freely licensed media file repository.5. Stepto RFT. Dispersity in polymer science

(IUPAC Recommendations 2009). Pure ApplChem 2009;81:351e3.

6. Matsumoto T, Horie S, Ochiumi T. Effect ofmolecular weight of ethylenedvinyl alcoholcopolymer on membrane properties. J MembrSci 1981;9:109e19.

7. Utracki LA. Polymer blends handbook, vols.1e2. SpringereVerlag; 2002.

8. Utracki LA. Commercial polymer blends.SpringereVerlag; 1998.

9. Utracki LA. Encyclopaedic dictionary ofcommercial polymer blends. ChemTecPublishing; 1994.

10. Flick EW.Plastics additivesean industrial guide.2nd ed. William Andrew Publishing/Noyes;1993.

11. Pritchard G. Plastics additivesean AeZ refer-ence. SpringereVerlag; 1998.


http://en.wikipedia.org/wiki/Dendronized_polymers

2 Introduction to the Weathering of Plastics

This chapter is split up into three sections. The firstsection discusses the chemical and physicalprocesses of the effects of weathering and ultraviolet(UV) light on plastics and polymers. The secondsection discusses additives used to improve weath-ering and UV-exposure performance. The thirdsection discusses the weather testing of both naturalexposure testing and accelerated exposure testing.

Because plastics are usually not neat polymers,they are formulated with pigments and additives thataffect also the weathering processes. In many cases,these materials improve the weathering performance,but in some cases the additives compromise theweathering performance.

There are several ways in which weather and theatmosphere can affect plastics:

1. Temperature and its variation

2. Humidity and its variation

3. Rain

4. Wind

5. Atmospheric gases, pollutants

6. Light (particularly UV)

The first four factors above have large physicaleffects, although temperature and humidity can alsohave chemical effects. The latter two can chemicallyaffect plastics. The physical and chemical affects arediscussed separately in the next few sections.

2.1 Physical Processes ofWeathering on Plastic Materials

There are several variables in weather exposurethat may apply physical forces to exposed plastics.These include heat, moisture and wind. Windblownparticles, dust and salt can have abrasive or erosiveeffects on plastic surfaces. They can scratch surfacesreducing gloss. Particles that remain on the surface

may also act to hold water and more dirt on thesurface longer.

Moisture in the form of rain or gas in the form ofhumidity can be absorbed by plastics. Nylon plasticsare particularly known for water absorption. Waterabsorption causes dimensional changes due toswelling. This can be a cyclical process with stresseswithin the plastics changing, leading to fatigue andcracking.

Cyclic variation of temperature induces alternatevolume expansion and contraction, which causesnonuniform stress like water absorption that can alsolead to fatigue and loss of physical properties.

The combined effect of moisture and temperaturecycles can cause severe deterioration in the form ofsurface cracks in plastic structures. In outdoorweathering, cyclic variation of humidity causesabsorption and desorption of moisture, and this, inturn, results in alternate swelling and shrinking ofthe surface material; owing to gradients in moisturecontent and temperature in the plastic material andto the presence of flaws, the cyclic dimensionalchanges that occur are not uniform in the directionnormal to the sheet or in a given plane parallel to thesurface. Hence they cause a variable, nonuniformstress that results in stress fatigue. When thetemperatures cross the freezing point of water cyclicfreezeethaw actions are possible. Temperature alsoaffects the rate of secondary chemical reactionsinvolved in deterioration upon exposure to UV lightdiscussed later.

Chalking is the formation of fine powder on thesurface of plastic or paint film due to weathering.Chalking can cause color fading. All paints andplastics chalk to some degree. It occurs as increasedamounts of organic polymer binder are removedfrom the surface, causing pigments to protrudethrough the surface producing a white, chalkyappearance. Chalking is a particular concern, sinceits onset causes color changedincreased lightnessand reduced chromaticity.




2.2 Chemical Effects ofAtmospheric Pollutants on PlasticMaterials

UV light can rapidly degrade some plastics ina process called photodegradation, which can lead tothe generation of chemical species that are oxidizedby oxygen or other chemicals in the air, nitrogendioxide, sulfur dioxide and other common pollu-tants. Ozone and sulfuric acid (from acid rain) candamage plastics. All these factors and more make theweathering process quite complex. Ozone, sulfurdioxide and nitrogen dioxide contaminants are dis-cussed in the next few paragraphs. However, there isno detailed data on the effects of these gases onplastics except for some limited data on ozoneexposure of some elastomers.

2.2.1 Ozone

Ozone is a triatomic molecule consisting of threeoxygen atoms (O3). It is much less stable and morereactive than the diatomic oxygen (O2). Ozone isformed from O2 by the action of ultraviolet light andatmospheric electrical discharges, and is present inlow concentrations throughout the Earth’s atmo-sphere though on average it makes up only 0.6 partsper million of the atmosphere.The presence of ozone in the air, even in very small

concentrations, markedly accelerates the aging ofpolymeric materials. Its normal mode of action isattack of the unsaturation (carbonecarbon doublebonds) in unsaturated polymers. This reaction gener-ally occurs in the steps shown in Fig. 2.1. Figure 2.2shows the scheme in a little more detail. The first stepis a cycloaddition of ozone to the olefin double bondto form an ozone olefin adduct referred to as the‘‘primary ozonide’’. This is an unstable speciesbecause it contains two very weak OeO bonds. Thesecond step in the ozonolysis mechanism is thedecomposition of the primary ozonide to carbonylcompounds and a carbonyl oxide. The carbonyl oxide

is considered to be the key intermediate in the C]Cbond ozonolysis mechanism. The third step in theozonolysis mechanism is the fate of the carbonyloxide, which depends on its source, as well as on itsenvironment.There is a limited amount of ozone exposure data

in the data sections of this book.

2.2.2 Sulfur Dioxide (SO2)

The sulfur dioxide (SO2) molecule is excited bynear-UV radiation, producing a reactive singlet ortriplet state, (SO2*). This state is long lived and in thepresence of air and light of about 313 nm wave-length, ozone may be produced by the followingreactions1:

SO2* þ O2 / SO4

SO4 þ O2 / SO3 þ O3

The reactive SO2* may also react with polymerswith saturated hydrocarbon segments.

SO2* þ ReH / RSO2H

There is no sulfur dioxide exposure data in thedata sections of this book.

Figure 2.1 The reaction scheme of ozone attack on a carbonecarbon double bond.

Figure 2.2 Ozone reaction with a double bond ina polymer.


2.2.3 Nitrogen Dioxide (NO2)

Nitrogen dioxide, NO2, is a reactive species as it isan odd electron molecule. Irradiation of NO2 withnear-UV light in presence of air may produce ozoneby the following reactions.1

NO2 þ hn / NOþ O

Oþ O2 þM / O3 þM

Double bonds are fairly easily attacked bynitrogen dioxide, as shown in Fig. 2.3. This reactioncan eventually lead to random chain scission orcross-linking or both.

There is no nitrogen dioxide exposure data in thedata sections of this book.

2.2.4 Photodegradation andPhoto OxidationdUVDegradation Processes

Radiation is a form of energy. There are two basictypes of radiation. One kind is particulate radiation,which involves subatomic fast-moving particles thathave both energy and mass. Particulate radiation isprimarily produced by disintegration of unstable atomsand includes Alpha and Beta particles. This book doesnot dealwith theparticulate typeof radiation.However,it is discussed in another book by this author.2

The second basic type of radiation is electromag-netic radiation. Electromagnetic radiation is a wavephenomenon commonly known as light. The type oflight of most concern with polymers and plastics isUV light. UV light has enough energy to causechemical changes to the polymers used in plasticsformulations, hence the concern.

There are three types of UV radiation:

� UV-A (wavelength 315e400 nm)

� UV-B (wavelength 280e315 nm)

� UV-C (wavelength 200e280 nm)

The shorter the wavelength the more energetic thelight. UV-B and UV-C are largely absorbed in the

atmosphere. The wavelengths of UV-A radiationrange between 320 and 400 nm. Ozone absorbs verylittle of the UV-A, so that is the UVwavelength rangethat is of primary concern in natural weathering.

The amount of light energy that impinges ona material exposed outdoor depends on the wave-length of the light, the intensity of the light and theangle of incidence. Light wavelength and intensity ina natural outdoor exposure is affected by manythings. Latitude affects the angle the light strikes thesurface. The amount of atmosphere the light passesthrough affects what is filtered out. This of coursechanges with the time of the year. Cloud-coverpatterns have an impact. Winds may suspend parti-cles that absorb or scatter light. Attitude affects howmuch atmosphere is available to absorb UV.

Light that strikes a plastic surface is basicallyeither reflected away from the surface or absorbed.The fate of the absorbed light is what is important inthe weathering process.

Photodegradation starts primarily when UV lightstrikes the polymer (R1-R2) and removes a hydrogenatom. This generates a radical indicated by (R1-R2

�);where the � is a reactive electron. This radical isunstable and reactive and it can do at least eightdifferent things to achieve lower energy as shown inTable 2.1.

The first four processes are photochemicalprocesses. The last four processes are photophysicalprocesses.

The photodegradation/photo oxidation process isconceptually fairly simple and is diagrammed inFig. 2.4. This simplified cycle applies to most poly-mers used in plastics and it is very useful inexplaining how the stabilizing additives discussedlater interrupt this cycle. Details of these reactionsmay be found for some of the polymers as eachplastic is introduced in the data chapters of this book.

2.3 Mechanisms of UVStabilization

The first step of the polymer degradation cycle isthe absorption of light (Step A Fig. 2.4) by a mole-cule that generates a radical (Step B in Fig. 2.4). Thisstep offers excellent opportunity to prevent or slowdown degradation. The idea is to keep the damaginglight from entering the plastic part to begin with.Stabilizing materials might be added to absorb,reflect or refract damaging light minimizing its

Figure 2.3 Reaction of nitrogen dioxide with carbonecarbon double bonds in a polymer.

2: INTRODUCTION TO THE WEATHERING OF PLASTICS 19

interaction with the polymer molecules. If light isabsorbed, it must not be reemitted at a damagingwavelength.

2.3.1 Absorption, Reflectionand Refraction

What happens to the energy of light that isabsorbed by plastics is critically important. Thepreferred result of absorption is conversion to heat.

Carbon black is one of the most efficient and wide-spread light absorbers. Carbon black has been anestablished light-stabilizing additive in polyolefins(and other polymers) for many years.1 It is believedto function as a simple physical screen, a UV ab-sorber. It also functions as a radical trap and aterminator of the free radical chains through whichthe photo-oxidative reactions are propagated, but thatis discussed later.Reflection of radiation at the material surface is

the most desired outcome because the light’s energyis redirected into the surrounding space and thereforeit does not affect plastic material. Reflection of lightis either specular (mirror-like) or diffuse (retainingthe energy, but losing the image) depending on thenature of the interface. When light strikes the surfaceof most plastic materials, it bounces off in all direc-tions, particularly if it is rough.Reflection may occur internally, off the surface of

an inorganic particle for instance. The energy in thatkind of light reflection energy can still be utilized forphotochemical processes because light reflectiondoes not alter its energy and it is still within theplastic material. It may also reflect off microscopicirregularities inside the material such as the grainboundaries of a polycrystalline material. The

Table 2.1 Reactions of Radicals Produced by Photodegradation.

Dissociation R1-R2� /R1þR2

� The radical may cause the polymerchain to break into two parts. The twoparts can be two polymer chains, or itcan be one polymer chain and one smallmolecule.

Reaction with otherspecies

R1-R2� þC/R1-CþR2

orR1-R2

� þC/R1-R2-C

The radical can react with anothermolecule (often oxygen); a break in thechain may accompany.

Isomerization R1-R2� /R2-R1

� The polymer can rearrange its structure.

Ionization R1-R2� /R1-R2

þ þ e� The polymer can kick off the electronforming an ion.

Deactivation R1-R2� þR1-R2

� /R1-R2þR1-R2 þenergy dissipation

The radical can be deactivated byreactive with another radical and give offenergy in the form of heat.

Intramolecular energytransfer

R1-R2� / �R1-R2 The radical can rearrange to another

part of the same molecule.

Intermolecular energytransfer

R1-R2� þR3-R4/R1-R2þR3-R4

� The radical can transfer to anotherneighboring polymer molecule.

Luminescence R1-R2� /R1-R2þ light The radical can give off energy in the

form of light.

Figure 2.4 Polymer degradation cycle.


reflective property of the plastic material changeswith time.

Refraction occurs when a light wave travels froma medium having a given refractive index toa medium with another refractive index at an angle.At the boundary between the media, the wave’sphase velocity is altered, usually causing a change indirection. The change of direction depends onrefractive indices according to Snell’s law as shownin Fig. 2.5.

Figure 2.6 schematically depicts a cross-section oftwo identically white-pigmented films and howdifferences in pigment refractive index affectopacity. In the thick film containing a high refractive-index pigment, light is bent more than in the filmcontaining the low refractive index, with the resultthat light travels a shorter path in the film and doesnot penetrate as deeply. Both upper films appearopaque and white, because no absorbing particles arepresent, and practically all incident light is returnedto the surface. However, for the thin film example atthe bottom of Fig. 2.6, the light can pass through thefilm making it more transparent.

To understand why titanium dioxide, especially therutile form, offers such great advantages in hidingpower, it is necessary only to compare the refractiveindex of rutile TiO2 to the refractive indices of anataseTiO2, other commercial white pigments and polymersystems as shown in Table 2.2. In general, the greaterthe difference between the refractive indexes of thepigment and that of the polymer matrix in which it isdispersed, the greater the light scattering.

2.4 UV Stabilizers

This section will cover examples of the differenttypes of additive materials used to improve the

Figure 2.5 Refraction and Snell’s Law.

Figure 2.6 The effect of film thick-ness and pigment refractive indexon the path of light.


resistance of plastics to UVexposures. The chemistryof their mode of stabilization will be discussed aswill some of the chemical structures.

2.4.1 UV Absorbers

UVabsorbers function by preferentially absorbingharmful UV radiation and dissipating it as thermalenergy. They act primarily in Step A in Fig. 2.4. TheUV absorbers dissipate the absorbed light energyfrom UV rays as heat by reversible intramolecularproton transfer, as shown in Fig. 2.7. UV absorbersshould absorb UV light in the 290e400 nm range butalso be transparent to other radiation, i.e. be colorlessin the visible spectrum. Benzophenones and benzo-triazoles are common UVabsorbers. There are manyto choose from and the structural differences mayseem small. Compare the o-hydroxy benzophenonestructure in Fig. 2.7 to the 2-hydroxy-4-octyloxybenzophenone in Fig. 2.8; the only differ-ence is the OeC8H17 side group. The side groups canaffect the compatibility of the UV additive with theparticular polymer formulation.

The chemical structures of some common benzo-phenone UV stabilizers are shown in Figs 2.8and 2.9.The chemical structures of some common benzo-

triazoles UV stabilizers are shown in Figs 2.10and 2.11.

2.4.2 Hindered Amine Stabilizers

Another type of UV stabilizer is known ashindered amine light stabilizer (abbreviated asHALS). These are derivatives of 2,2,6,6-tetramethylpiperidine shown in Fig. 2.12. These are extremely

Table 2.2 Indices of Refraction for Some White Pigments and Common Polymers

White Pigment Refractive Index Plastic Refractive Index

Rutile TiO2 2.73 Polystyrene 1.60

Anatase TiO2 2.55 Polycarbonate 1.59

Antimony oxide 2.09e2.29 SAN 1.56

Zinc oxide 2.02 Polyethylene 1.50e1.54

Basic carbonate, white lead 1.94e2.09 Acrylic 1.49

Lithopone 1.84 Polyvinyl chloride 1.48

Clay 1.65 e e

Magnesium silicate 1.65 e e

Barytes (BaSO4) 1.64 e e

Calcium carbonate (CaCO3) 1.63 e e

Figure 2.7 Reversible intramolecular proton transferin o-hydroxy benzophenone converts UV light energyto heat.

Figure 2.8 Chemical structure of 2-hydroxy-4-octyloxybenzophenone [Cytec Cyasorb� UV 531].

Figure 2.9 Chemical structure of 2,4-di-hydroxybenzophenone [Everlight Chemical Eversorb10, Chemtura Lowilite� 24].


efficient stabilizers against light-induced degradationof most polymers. HALS do not absorb UV radiationlike UV absorbers described in the previous section.As shown in reaction below, they form nitroxylradicals that act as radical scavengers to inhibitdegradation of the polymer:

R1N$þ R$ / R1NR

This occurs in Steps B, C and E of the polymerdegradation cycle of Fig. 2.4.

Significant levels of stabilization are achievedat relatively low concentrations. HALS are typi-cally regenerated and so have high efficiencyand longevity. HALS are usually large complexmolecules.

The chemical structures of some common HALSare shown in Figs 2.13 and 2.14.

2.4.3 Phenolic Antioxidants

Phenolic antioxidants are compounds that caninterfere with the oxidative cycle thus inhibitingor slowing the photooxidative degradation of poly-mers. They act to interrupt the oxidative processillustrated in Fig. 2.4 Step C. They do this byinterrupting the primary oxidation cycle by re-moving the propagating radicals. Such compoundsare also called Chain-Breaking Antioxidants andexamples include the hindered phenols and aromaticamines.

The chemical structures of some common phenolicantioxidants are shown in Figs 2.15 and 2.16.

Figure 2.10 Chemical structure of 2-(2H-benzotria-zol-2-yl)-p-cresol [Ciba� Tinuvin� P].

Figure 2.11 Chemical structure of 2-(2H-benzotria-zole-2-yl)-4,6-di-tert-pentylphenol [Ciba� Tinuvin�

328].

Figure 2.12 Chemical structure of 2,2,6,6-tetramethyl piperidine and its nitroxyl radical.

Figure 2.13 Chemical structure of Ciba�Chimassorb� 119, Chemtura Lowilite� 19.

Figure 2.14 Chemical structureof bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate [Ciba� Tinuvin� 700].


2.4.4 Phosphites andPhosphonites

Phosphite antioxidants function by decomposingperoxides (see Fig. 2.4 Steps C and D) and provideprotection to adhesives, plastics and coatings duringhigh temperature processing but not during end-useat elevated temperatures. The most importantpreventive mechanism is the hydroperoxide decom-position where the hydroperoxides are transformedinto nonradical, nonreactive and thermally stableproducts, as shown in the reaction schematic below:

ROOH þ PðOR0Þ3 / ROH þ O]PðOR0Þ3Hydroperoxide Phosphite alcohol

Combinations with phenolic antioxidants oftenshow synergistic performance and are widely used.

The chemical structures of some common phos-phite antioxidants are shown in Figs 2.17 and 2.18.

2.4.5 Inorganic Screeners

Inorganic screeners are additives such as carbonblack, titaniumdioxide, zinc oxide, ceriumoctoate andceriumetitanium pyrophosphate. They function byconvertingUVlight to heat inStepAofFigure 2-X likeUVAbsorbers, which are organic molecules.Carbon Black: Fig. 2.19 shows the absorption of

UV light vs. carbon black content in a polyolefin.While all carbon blacks are good absorbers of UV

they are not equally so. UV stabilization increaseswith decreased primary particle and aggregate size.This is a function of the increase in surface area ofcarbon black that is available to absorb the light.Nonblack pigments can also be good UV-light

absorbers.Titanium Dioxide: Titanium dioxide (TiO2) is

a white pigment and one would assume that it reflectsUV light like it does visible light. That assumptionwould be incorrect. Figure 2.20 shows that visible lightis indeed strongly reflected, but aswavelengths shorteninto the UV range that reflectance drops dramatically.However, TiO2, even though it is white, absorbs UVstrongly as shown in Fig. 2.21. Zinc Oxide has similarbehavior.

Figure 2.15 Chemical structure of ethylene-bis(oxy-ethylene)-bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)-pro-pionate) Phenolic Antioxidant [Ciba� Irganox� 245].

Figure 2.16 Chemical structure of 2,6,-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5,-triazine-2-ylamino) phenolPhenolic Antioxidant [Ciba� Irganox� 565].

Figure 2.17 Chemical structure of trinonylphenolphosphite [Chemtura Weston� 399].

Figure 2.18 Chemical structure ofbis-(2,4-di-t-butylphenol) pentaer-ythritol diphosphite [Ciba�Irgafos� 126].


Figure 2.19 Absorption of UVlight vs. carbon black content ina Low-density polyethylene film.

Figure 2.20 Reflection of UV lightvs. wavelength by TitaniumDioxide.3

Figure 2.21 Absorption of UV lightby titanium dioxide of differentparticle sizes.


2.4.6 Thiosynergists

Like phosphites and phosphonites, sulfur-basedthiosynergists also function by decomposing hydro-peroxides. Thiosynergists react according to thegeneral reaction shown if Fig. 2.22, generatingsulfoxides and sulfones.The chemical structures of some common thio-

synergists are shown in Figs 2.23 and 2.24.

2.4.7 Optical Brighteners

Optical brighteners, optical brightening agents,fluorescent brightening agents or fluorescent whit-ening agents are dyes that absorb light in the UVandviolet region (usually 340e370 nm) of the electro-magnetic spectrum, and reemit light in the blue

region (typically 420e470 nm). Fluorescent activityis a short-term or rapid-emission response, unlikephosphorescence, which is a delayed emission. Theseadditives are often used to enhance the appearance ofcolor of fabric, paper, and plastics causing a “whit-ening” effect, making materials look less yellow byincreasing the overall amount of blue light reflected.This is graphically demonstrated in Fig. 2.25, whichshows the impinging exciting spectrum and theemission spectrum for bis-benzoxazolyl-stilbenedawidely used optical brightener for thermoplastics thestructure of which is shown in Fig. 2.26. Figure 2.27shows the reflectance vs. wavelength of polyestercomposite with and without optical brightener.Basic class types of brighteners include:

1. Triazine-stilbenes (di-, tetra- or hexa-sulfonated)

2. Coumarins

3. Imidazolines

4. Diazoles

5. Triazoles

6. Benzoxazolines

7. Biphenyl-stilbenes

The chemical structures of some common opticalbrighteners are shown in Figs 2.28 and 2.29.

2.4.8 Acid Scavenger

Acid scavengers neutralize catalyst residues andother acidic species in plastics. Common acid scav-engers include hydrotalcite, calcium and zinc stea-rates. Hydrotalcite is a naturally occurring mineral ofchemical composition Mg6Al2(OH)16CO3 4H2O. Itreacts with acids producing carbon dioxide andwater.

Figure 2.22 Hydroperoxides are decomposed bythiosynergists.

Figure 2.23 Chemical structure of didodecyl-3,30-thiodipropionate [Ciba� Irganox� PS 800].

Figure 2.24 Chemical structure of 2,20-thiodiethylene bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate][Chemtura Anox� 70].


Figure 2.26 Chemical structure ofbis-benzoxazolyl-stilbene.

Figure 2.25 Excitation and emis-sion curves for bis-benzoxazolyl-stilbene.4

Figure 2.27 Reflectances vs.wavelength of polyester compositewith and without optical brightener.4

Figure 2.28 Chemical structure ofoptical brightener 2,20-(2,5-thiophene-diyl)bis(5-tert-butylbenzoxazole) [MayzoBenetex� OB Plus].


2.4.9 Quencher

Nickel quenchers are light stabilizers that are ableto take over the energy absorbed by the chromo-phores and dissipate it either as heat or as fluorescentor phosphorescent radiation to prevent degradation.Nickel quenchers, unlike stabilization packagesbased on HALS, are unlikely to interact with pesti-cides, sulfur, halogen or phosphorous-based acidicsubstances. They are mainly used for agriculturalfilm applications (greenhouse and mulch films)where they offer the best balance between UVprotection and interaction with pesticides. Chem-tura’s LOWILITE� nickel quenchers work syner-gistically with UVabsorbers and are often combinedto take advantage of this. The structure of onequencher is shown in Fig. 2.30.

2.4.10 Synergistic Mixturesof Stabilizers

Stabilizer packages in plastics are usually mixtures.Numerous examples of synergism are available inpractical applications and literature.

They involve the following pairs of UV stabilizers:

� HAS and HAS

� HAS and UV absorbers

� HAS and phenolic antioxidants

� HAS and amines

� UV absorbers and phenolic antioxidants

� UV absorbers and dithiocarbamates

� UV absorbers and Ni chelates

� phenolic antioxidants and dithiopropionate

In some cases, mixtures can result in poorer per-formancedthis is called antagonism.

� HAS and HAS

� HAS and phenolic antioxidants

� HAS and Ni dithiocarbamate

� HAS and UV absorbers

� inorganic fillers, screeners, and pigments and allstabilizers

2.5 Testing

Testing for weathering performance can be assimple as putting test plaques outside for years.Unfortunately, if plastic materials are formulated forlong life it takes years to get measurable change.This approach is important and areas around theworld that have extreme weather are used as testsites. As always, the scientists looked for ways toaccelerate degradation. Many test methods have beendeveloped to accelerate outdoor exposure and byusing laboratory-built instruments to accelerate time.The rest of this chapter is focused on weathering andUV testing.

2.5.1 Indoor and InteriorExposures

During indoor exposure, products are subjected toUV radiation from fluorescent lights as well as fromglass-filtered UV rays transmitted through windows.The type of light source, its energy flux and itsdistance from the specimens determine the intensityof the radiation impinging on the surface of the part.Glass of any type acts as a filter on the sunlight

spectrum. The shorter, most damaging wavelengths

Figure 2.29 Chemical structure of optical brightener2,20-(1,2-ethylenediyldi-4,1-phenylene)bisbenzoxa-zole [Eastman Eastobrite OB-1].

Figure 2.30 The chemical structure of (2,20-thio-bis(4-tert-octyl-phenolato))-N-butylamine-nickel(II)[Chemtura Lowilite� Q84].


are the most greatly affected. Ordinary window glassis essentially transparent to light above 370 nm, withvisible light generally considered above 390 nm.However, the filtering effect becomes more pro-nounced with decreasing wavelength. Automotivewindshield glass is thicker than housewindow glass; itacts as amore efficient filter. Safety features associatedwith windshield glass (e.g. tinting and plastic) add tothe filtering efficiency. Almost all UV light is filteredout by windshield glass, and the most damagingwavelengths below310 nmare completely filtered out.

Indoor exposure studies are rare.

2.5.2 Outdoor Testing

Real-time weathering data from natural environ-ment exposure programs remain the standard towhich all other weathering data are compared. Threeof the most commonly used harsh aging sites areArizona, Florida and Japan. Arizona is importantbecause of its high annual radiation and ambienttemperature. Southern Florida is unique because ofits high radiation combined with high rainfall andhumidity. Figure 2.31 shows Q-Lab� Corporation’sFlorida exposure site. Florida and Arizona havebecome United States and international referenceclimates for gauging the durability of materials sincethey represent the worst case for applications in thenorthern hemisphere.

With all outdoor tests, it is important to be awareof bias introduced by the choice of location. InMiami, Florida, there are approximately 110 sunhours per month. This is a total of 1200e1300 sun

hours per year. With a 45˚ due south exposure, testspecimens receive approximately 150,000 langleysper year. Figure 2.32 shows a typical exposure rack,this one holding painted samples in an unbackedconfiguration. Paint and coating panels are similarlyexposed. Most often properties like color change,gloss change and chalking are evaluated and the testpieces continue on being exposed. To do destructivetesting such as tensile strength, multiple coupons areexposed with some being removed.

2.5.3 Conventional Aging

This test method, which may occur in manydifferent geographic locations (e.g. Florida, Arizona,and Okinawa, Japan), is a real-time exposure at a 45˚tilt from the horizontal. Direct exposures are inten-ded for materials that will be used outdoors andsubjected to all elements of weather. Exposure timesare generally 6, 12, 24 and 48 months. Location is animportant factor in the harshness of this test. Theassumption is that test results from a hostile envi-ronment will prevail in more moderate conditions.

There are many variations to conventional outdoorexposures. The rack holding the test samples hasseveral different configurations.

Unbacked racks, Fig. 2.32, expose materials sothat the portion of the specimen being evaluated issubject to the effect of weathering on all sides. Whilethe racks are generally oriented South, there arevariations in the angle, with popular exposure anglesincluding 90˚, 45˚ and 5˚ and at latitude angles fromhorizontal.

Figure 2.31 Aerial photo of Q-Lab� Corporation’sFlorida exposure site (photo courtesy of Q-Lab�

Corporation, www.Q-Lab�.com). (For color versionof this figure, the reader is referred to the onlineversion of this book.)

Figure 2.32 Typical outdoor exposure rack, this onebeing with open backs (photo courtesy of Q-Lab�

Corporation, www.Q-Lab�.com). (For color versionof this figure, the reader is referred to the onlineversion of this book.)


http://www.Q-Lab%26reg;.com




Backing test specimens with substrate may resultin mild acceleration over unbacked exposures. Thebacking is typically exterior grade plywood. The solidbacking typically results in greater total wet time fromslower evaporation and in higher temperature expo-sures than an open backmounting. Occasionally, somebacked exposures utilize black painted substrates toabsorb solar energy for increased specimen-exposuretemperatures.Unbacked and backed exposure methods are

covered by standard procedures: ASTM G7 (Stan-dard Practice for Atmospheric EnvironmentalExposure Testing of Nonmetallic Materials), ASTMD1435 (Standard Practice for Outdoor Weathering ofPlastics) and SAE J1976 (Outdoor Weathering ofExterior Material).There are also black box (see Fig. 2.33) and black

box under glass exposure rack variations that may beused for specialized automotive testing situations.This type of exposure is usually only for coatings.The purpose of a Black Box Exposure is to imitatethe conditions found on the trunk and hood of anautomobile. The typical exposure frame is analuminum box 5 ft� 12 ft� 9 in. deep. The testpanels form the top surface of the box when they arein place. The top surface must always be completelyenclosed. Black Box Exposures typically result inhigher exposure temperatures and a greater total wettime than open backed exposures. The Black Boxexposure method is covered by ASTM D4141(Standard Practice for Conducting Black Box andSolar Concentrating Exposures of Coatings).Many automotive materials are not designed to be

directly exposed to weather, but they may be exposed

during use through glass. Under Glass Exposures arerack exposures, both backed and unbacked configu-rations, that support specimens beneath glazing ofappropriate glass material as in Fig. 2.34. The glassenclosure is ventilated allowing natural humidity in.Tracking racks track the sun. Track racks often

employ two axes of movement. Changing the anglefrom horizontal often is not continuous but changedfour times per year accommodates the elevation ofthe sun. A second pivot attaches the specimenmounting frame 90˚ to the pivot for elevation. Slow-stepping motors drive the azimuth pivot orienting thespecimen’s surface perpendicular to the sun’s raysthroughout the day.There are also variations that are called Controlled

Temperature and Humidity. These are tracking racksunder glass that track the sun by adjusting bothangles of exposure continuously as in Fig. 2.35.

Figure 2.33 Black Box Outdoor exposure rack(photo courtesy of Q-Lab� Corporation, www.Q-Lab�.com). (For color version of this figure, thereader is referred to the online version of this book.)

Figure 2.34 Exposure under glass (photo courtesyof Q-Lab� Corporation, www.Q-Lab�.com). (Forcolor version of this figure, the reader is referred tothe online version of this book.)

Figure 2.35 Exposure under glass with tracking(photo courtesy of Q-Lab� Corporation, www.Q-Lab�.com). (For color version of this figure, thereader is referred to the online version of this book.)










There are heating elements to warm the environmentwhen necessary, often at night. They are oftenoperated at 70 ˚C during the day and 38 ˚C at night.

2.5.4 Conventional Agingwith Spray

The conventional aging with spray test method isreal-time exposure at a 45˚ tilt from the horizontalwith a water spray used to induce moisture-weath-ering conditions. The introduction of moisture playsan important role in improving both the relevanceand reproducibility of the weathering test results.The purpose of wetting is twofold. First, the intro-duction of water in an otherwise arid climate inducesand accelerates some degradation modes that do notoccur as rapidly, if at all, without moisture. Second,a thermal shock causes a reduction in specimensurface temperatures, as much as 14 ˚C (57 ˚F). Thisresults in physical stresses that accelerate thedegradation process. Spray nozzles are mountedabove the face of the rack at points distributed toensure uniform wetting of the entire exposed area.Distilled water is sprayed for 4 h preceding sunrise tosoak the samples, and then 20 times during the day in15-s bursts. Direct exposures are intended for mate-rials that will be used outdoors and subjected toall elements of weather. Like conventional aging,exposure times are generally 6, 12, 24 and 48months. Location is an important factor in theharshness of this test. With all outdoor tests, it isimportant to be aware of bias introduced by thechoice of location. A variation of conventional agingwith spray is to use a tracking rack.

When the test panel is coated substrate sometimesSalt-Accelerated Outdoor Exposure is done. Thisexposure method uses an outdoor exposure anda twice weekly spray with a 5% salt solution. This isdone manually by a technician as shown in Fig. 2.36.The panels are sprayed until the surface is com-pletely soaked when the panels are dry so thatmaximum absorption occurs. This type of exposureis known as a “Scab Corrosion” test and has beenproven to be a reliable method for predicting long-term cosmetic corrosion of coated metals.

2.5.5 Accelerated Outdoor Tests

In outdoor tests, the usual standard procedure callsfor specimen exposure on racks facing due south at

an angle of 45˚. These are conditions that offera maximum direct sunlight exposure and intensity.This tilt is also preferable since it allows for somedrainage and dirt wash-off during rains. Sources ofradiation for outdoor exposure tests include bothdirect and reflected sunlight. In a further attempt toaccelerate outdoor effects, many studies are con-ducted in tropical as well as hot climates such asFlorida and Arizona in the United States, andPanama, Germany, and Japan to obtain the mostwide-ranging and severe environments possible.Outdoor accelerated weathering is a relatively recenttechnique. It relies heavily on technology to followthe track of the sun and to keep the sample ata constant temperature.

2.5.5.1 Equatorial Mount with Mirrorsfor Acceleration (EMMA�)

Natural sunlight and special reflecting mirrors areused to concentrate sunlight to the intensity of abouteight suns. The test apparatus, shown in Fig. 2.37follows the sun track with mirrors positioned astangents to an imaginary parabolic trough. The axisis oriented in a northesouth direction, with the northelevation having the capability for periodic altitudeadjustments. A blower directs air over and under thesamples to cool the specimens. This limits theincrease in surface temperatures of most materials to10 ˚C (50 ˚F) above the maximum service tempera-ture that is reached by identically mounted samplesexposed to direct sunlight at the same times andlocations without concentration. Exposed periods of

Figure 2.36 Salt solution is manually sprayed onexposure panels twice a week (photo courtesy ofQ-Lab� Corporation, www.Q-Lab�.com).




6 and 12 months have been correlated to about 2.5and 5 years of actual aging in a Florida environment,respectively.Variations to EMMA� include under glass expo-

sures (actually under glass filters).

2.5.5.2 Equatorial Mount with Mirrorsfor Acceleration Plus Water(EMMAqua�)

Natural sunlight and special reflecting mirrors areused to concentrate sunlight to the intensity of abouteight suns. In addition to intensifying the power of thesun, a water spray is used to induce moisture-weath-ering conditions. The test apparatus follows the suntrack with mirrors positioned as tangents to an imagi-nary parabolic trough. The axis is oriented in a northesouth direction, with the north elevation havingthe capability for periodic altitude adjustments. Ablower directs air over and under the samples to coolthe specimens. This limits the increase in surfacetemperatures of most materials to 10 ˚C (50 ˚F) abovethe maximum service temperature that is reached byidenticallymounted samples exposed todirect sunlightat the same times and locations without concentration.Exposure to EMMAqua� is considered to be a veryharsh exposure.There areEMMAqua� variations that includenight-

time wetting cycles, and full sun-tracking systems(called EMMAqua� Plus). Another variation is

EMMAqua� Plus with Soak-Freeze Cycles. Theexposure is done at night by manually moving the testplaques to a laboratory freezer for a specified amountof time.

2.5.5.3 Ultra-accelerated ExposureTesting

Atlas in partnership with the National RenewableEnergy Laboratory (NREL) and the Russian Instituteof Laser Optical Technology (ILOT) under a U.S.Department of Energy (DOE) program developedUltra-Accelerated Exposure Testing. This is solarconcentrator technology. The device tracks the sunwhile concentrating reflected sunlight on test speci-mens mounted in a target area. The patented mirrorsystem has very high reflectance in the UVand near-visible wavelength ranges while attenuating reflec-tance in the longer wavelength visible and IR portionsof the solar spectrum. This allows for very highconcentrations ofUVenergywithout excessive heatingof test samples. Using multiple focusing mirrorsarranged on the curve of a 10m sphere, the UVenergymay be variably concentrated on a target areaapproximately 10 cm� 10 cm. Custom mounting andcooling can be added depending upon specificmaterialexposure requirements. Optically the mirror systemhas a direct normal 100/1 concentration factor. Apicture of this exposure device in shown in Fig. 2.38.

2.5.6 Artificial Accelerated Tests

Artificial weathering devices, tests that use artifi-cial light sources, are used to measure the resistanceof materials to weather degradation. These testsprovide reliable data in a shorter period of time than

Figure 2.37 The Equatorial mount with mirrors(EMMA�) apparatus (photo courtesy of Atlas Mate-rial testing Technology LLC). (For color version ofthis figure, the reader is referred to the online versionof this book.)

Figure 2.38 The Ultra-accelerated exposure testingapparatus (photo courtesy of Atlas Material testingTechnology LLC). For color version of this figure, thereader is referred to the online version of this book.


outdoor testing. Light sources for the acceleratedtests include filtered long arc xenon, fluorescentmetal halide lamps and carbon arc. Less commonlyused light sources include mercury vapor and tung-sten lamps. Each light source has its own inherentbenefits of which a weathering experimenter must beaware. Table 2.3 summarizes the properties and useof these lamps sources, common test instrumentsusing the light source and associated test standards.Most of the associated test instruments are discussedin the following sections.

Xenon arc light sources, such as those employed inAtlas’s Weather-Ometer� and Q-Lab�’s Q-Sun�

Xenon Arc Test Chamber, are widely used for testingcolor change resistance. Fluorescent lamps, such asthose used in Q-Lab�’s QUV� Weathering Testerand Atlas’s UVTest, produce only UV light andprovide a more stable UV spectrum over time,making them useful for testing physical propertychanges in plastics and coatings.

Often reported exposure data contain several termsare that describe the light brightness or intensity.These are listed in Table 2.4.

The relative spectra output of several light sourcesas compared to sunlight are shown in Figs 2.39e2.41.

2.5.6.1 Xenon Arc

Xenon arc is a precision gas discharge lamp sealedin a quartz tube. It can be water cooled or air cooled.It produces light by passing electricity throughionized xenon gas at high pressure. Througha combination of filters used to reduce unwantedradiation, the xenon (long) arc simulates UV andvisible solar radiation more closely than any otherartificial light source. It is widely preferred as a lightsource when the material to be tested will be exposedto natural sunlight.7

Automotive test SAE J1885 Accelerated Exposureof Automotive Interior Trim Components Usinga Controlled Irradiance Water Cooled Xenon-ArcApparatus is used for testing interior automotivematerials and calls for xenon arc exposure withquartz-inner and borosilicate-outer filters. This filtercombination transmits short-wave UV radiation aslow as 275 nm. Automotive test SAE J1960 Accel-erated Exposure of Automotive Exterior MaterialsUsing a Controlled Irradiance Water-cooled XenonArc Apparatus is used to evaluate exteriorautomotive materials by accelerated means. The testuses a quartz/borosilicate-S-filter combination. Most

engineers involved with this test state that2500 kJ/m2 is approximately two years of Floridatesting. However, the spectral power distribution(light intensity vs. wavelength) of the SAE J1960 testmethod does not exactly match actual Miamisunlight and can be a nonpredictive test for somematerials. Some automotive companies use differentoptical filter combinations (Boro-S/Boro-S or CIRA/Soda Lime) that more closely match true Miamisolar radiation. In addition, the comparison based ona single factor (solar radiant energy) does not takeinto account the other weathering factors such asheat, moisture, etc., and their synergistic effects,which magnify the effects of solar radiation.7 Anexample of a test instrument is the Xenotest by Atlas,shown in Fig. 2.42. Xenotest can be fitted withvarious filters to control the UVexposure type and itcan also include humidity.

To simulate rain, the exposure instruments such asthe Atlas Weather-Ometer� (shown in Fig. 2.43) andQ-Panel� Q-Sun� are programmable or selectablewith additional variables, including light sourcefilters, light and dark cycles, temperature, humidityand water spray. Typical exposure cycles for differentweathering instruments are given in Tables 2.5e2.7.

Xenon light must be properly filtered to achievethe appropriate spectrum for each particular appli-cation. Differences in spectra may affect both thespeed and the type of degradation. Three categoriesof filters are available to simulate a variety of serviceenvironments. The application or test methoddictates which filters should be used.

Daylight filters are used to simulate direct, noonsummer sunlight. They provide the best correlationto natural exposures for most applications. WindowGlass Filters produce spectra equivalent to sunlightcoming through window glass. Extended UV Filtersallow excess UV, below the normal cut-on of naturalsunlight. They are used to produce faster or moresevere test results.

2.5.6.2 Fluorescent or QUV�

The UV test procedure simulates long-termoutdoor exposure to sunlight, rain and dew byexposing materials to alternating cycles of UV-A orUV-B light and moisture at controlled elevatedtemperatures. These are the most aggressivecomponents of weatheringdUV radiation, moistureand heat. UV radiation within a desired UV wave-length is provided through the use of fluorescent


Table 2.3 Principal Light Sources used for Accelerated Weathering5

Type Wavelength Instruments FiltersMoistureOption Standardsd Commentsa

FluorescentUV lamp

UVB-313: 275e380 nm; UVA-340:295e400 nm; UVA-351: 310e400 nm

QUV� (Q-Lab�)UV2000 (Atlas)

No standard spectrafrom lamps used

Condensation;water spraypossible

ISO 4892-3ASTMD4329SAE J2020

Only UV. Significantacceleration, butespecially UVB has lowcorrelation with naturalsunlight. UVA-340 givesgood simulation ofdaylight in 300e340 nmrange while UVA-351simulates sunlightbehind glass.

Xenon arc 270e800 nm (closematch for sunlight)

Weather-Ometer� (Atlas)Xenotest�

(Atlas)b Q-Sun�

(Q-Lab�)

Yes combinations ofquartz and borosilicate,for cutoff <290(daylight) or <300 nm(window)

Water spray;relativehumiditycontrolled

ISO 4892-2ASTMD2565NF C 20-540UL 1581DIN 53387c

UV/VIS. Most commonmethod; goodcorrelation with naturalsunlight. Irradiancetypically 0.2e1.7W/(m2 nm) at 340 nm.Equipment expensive topurchase and maintain.

Mercuryvapor

200e400 nm; mainpeaks at 254, 313 and366 nm

SEPAP 12/24(MPC/Omya)

Yes wavelengths<290 nm are cut off

No NF C 32-062-2

Mainly UV light.4� 400W mercury arclamps. Some concernsregarding stability oflamps.

SEPAP 12/24H(MPC/Omya)

Yes

Carbon arc 300e800 nm;intense bands at 358and 386 nm

Weather-Ometer� (Atlas)

Yes Water spray;RH

ISO 4892-4ASTMD1499UL 1581

UV/VIS, but too high UVcompared to sunlight.Not frequently used.

aIrradiance is controlled either on narrow-band (e.g. 340, 420 nm), broad-band (e.g. 300e400 nm) or wide-band (e.g. 300e800 nm); in ISO 4892 typical irradiancelevels (300e400 nm) of 45 W/m2 for fluorescent UV instruments and 50e60 W/m2 for xenon arc instruments are cited.bXenon arc instrument without moisture optionare available, e.g. Suntest (Atlas). Such instruments do not conform to standards like ISO 4892-2.cDiscontinued in favor of ISO 4892.dNF, Bureau de Normalisationdu Systeme Francais de Normalisation; ISO, International Organization for Standardization; ASTM, ASTM International(American Society for Testing andMaterials); UL, Underwriters Laboratorie; DIN, Deutsches Institut fur Normung; SAE, SAE International (Society of Automotive Engineers).

34

THEEFFECT

OFUV

LIG

HT

ANDW

EATHER

ONPLASTIC

SANDELASTOMERS

lamps. Moisture is provided by forced condensationand temperature is controlled by heaters.9 Fig. 2.44shows a picture of one of Q-Lab�’s QUV� exposureinstruments.

Although UV light makes up only about 5% ofsunlight, it is responsible for most of the damagecaused to durable materials exposed outdoors. To

simulate the damage caused by UV rays, it is notnecessary to reproduce the entire spectrum ofsunlight. In many cases it is only necessary tosimulate the short-wavelength UV.

Each type of lamp differs in the total amount ofUV energy emitted and in its spectrum. FluorescentUV lamps are usually categorized as UV-A or UV-B

Table 2.4 Definition of Terms Related to Solar and Artificial Light Exposure5

Term Definition Unit

Irradiance Radiant flux incident on a surface per unit area W/m2

Spectral irradiance Irradiance as a function of wavelength W/(m2$nm)

Radiant exposure, E Time integral of irradiance J/m2

Spectral radiant exposure Radiant exposure as a function of wavelength J/(m2$nm)

Figure 2.39 The relative spectral outputof Xenon Arc as compared to sunlight.6

Figure 2.40 The relative spectral outputof Metal Halide lamps as compared tosunlight.6


lamps, depending on the region into which most oftheir output falls.11

� UV-A lamps are useful for comparing differenttypes of polymers. Because UV-A lamps do nothave any UV output below 295 nm, they do notdegrade materials as quickly as UV-B lamps.UV-A lamps usually provide good correlationwith actual outdoor weathering.11

� UVA-340 lamps provide the best possible simula-tion of sunlight in the critical short wavelength

from 365 nm down to the solar cutoff of 295 nm.It is most useful in comparison tests of differentformulations.11

� UVA-351 lamps simulate the UV portion ofsunlight filtered through window glass. It is mostuseful for simulating interior applications.11

� UV-B lamps are used for fast, cost-effectivetesting of durable materials. All UV-B lampsemit short wavelength

� UV below the solar cutoff of 295 nm. Althoughthis short-wave UV accelerates testing, it cansometimes lead to anomalous results.11

� UVB-313 is the most widely used UV-B lamp fortesting very durable applications. It is especiallyuseful to maximize acceleration when testing

Figure 2.41 The relative spectral outputof Carbon Arc as compared to sunlight.6

Figure 2.42 Atlas Xenotest (photo courtesy of AtlasMaterial testing Technology LLC). For color versionof this figure, the reader is referred to the onlineversion of this book.

Figure 2.43 Atlas Ci4000 Weather-Ometer�/Fade-Ometer� (photo courtesy of Atlas Material testingTechnology LLC). For color version of this figure, thereader is referred to the online version of this book.


Table 2.5 Typical Cycles Used in Operation of Xenon Arc-Weathering Instruments8

FilterIrradianceW/(m2�nm)

Wavelength(nm) Cycle-min RH %

Temperature(Black Panel) ˚C

WaterSpray

Daylight 0.35 340 Light-102Light-18

NcNc

63� 2.5Nc

NoYes

Daylight 0.35 340 Light-102Light-18Dark-360

NcNc95� 4

63�2.5Nc24� 2.5

NoYesNo

Daylight 0.35 340 Light-90Light-30

70� 5Nc

77� 3No

NoYes

Daylight 180W/m2 300e400 Light-102Light-18

NcNc

63� 3Nc

NoYes

Window glass 0.30 340 Light-100% 55� 5 55� 2 No

Window glass 1.10 420 Light-102Light-18

35� 5Nc

63� 2.5Nc

NoYes

Window glass 1.10 420 Light-228Dark-60

35� 590� 5

63�2.543� 2

NoNo

Window glass 162W/m2 300e400 Light-100% 50� 5 89� 3 No

Window glass 0.55 340 Light-40Light-20Light-60Dark-60

50� 5Nc50� 590� 5

70� 2Nc70� 238� 2

NoYesb

NoYesa

Window glass 0.55 340 Light-228Dark-60

50� 590� 5

89� 338� 2

NoNo

Nc, no control, wavelength is given for the measured value of irradiance.aface. bback.

Table 2.6 Typical Cycles Used in Operation of Fluorescent Lamp (UV Type) Weathering Instruments8

Lamp Irradiance W/(m2�nm) At Wavelength (nm) Cycle-hoursTemperatureBlack Panel ˚C

UVA-340 0.77 340 UV-8Condensation-4

60� 350� 3


70� 350� 3


60� 350� 3

UVA-340 1.35 340 UV-8Water spray-0.25Condensation-4

60� 3No control, no light50� 3

UVB-313 0.63 310 UV-4Condensation-4

60� 350� 3


70� 350� 3


80� 350� 3


very durable applications like automotive coatingsand roofing materials.11

� QFS-40 is the original QUV� lamp. These lampsare also known as FS-40 or FS-40 UVB. It hasdemonstrated good correlation to outdoor expo-sures for gloss retention on automotive coatingsand for material integrity of plastics.11

Tests using fluorescent lamps are useful for relativerank comparisons between materials under specificconditions, but the comparison to service lifetimeperformance or correlation to outdoor exposures maynot bevalid. The best use of theUVlamps is for generalscreening tests such as checking for gross formulationerrors with an artificially harsh exposure.7

Test methods specifying the QUV� UV-340 lampinclude ASTM D4329 Standard Practice for Fluo-rescent UV Exposure of Plastics and ASTM D4587Standard Practice for Fluorescent UV-CondensationExposures of Paint and Related Coatings, ISO 4892Methods of exposure to laboratory light sources, andSAE J2020 Accelerated Exposure of AutomotiveExterior Materials Using a Fluorescent UV andCondensation Apparatus.

Table 2.7 Typical Cycles Used in Operation of Carbon Arc Weathering Instruments8

Filter Cycle-min RH % Temperature Black Panel ˚C Spray

Daylight Light-102Light-18Dark-360

No controlNo control95� 4

63� 3No control24� 2.5

NoYesNo

Daylight Light-240Light-240

No controlNo control

63� 3No control

NoYes

Daylight Light-720Light-720


63� 3No control

NoYes

Window glass Light-100% No control 63� 3 No

Enclosed carbon arc Light-102Light-18


63� 2.5No control

NoYes

Enclosed carbon arc Light-100% 30� 5% 63� 2.5 No

Enclosed carbon arc Light-228Dark-360

30� 5%90� 5%

63� 2.5No control

NoNo

Enclosed carbon arc Light-102Light-18Dark-240

No controlNo control95� 4

63� 2.5No control24� 2.5

NoYesNo



63� 2.5No control

NoYes



63� 2.5No control

NoYes

Enclosed carbon arc Light-100% 30% 63� 3 No

Figure 2.44 Photograph of a Q-Lab� QUV� testinstrument.10 For color version of this figure, thereader is referred to the online version of this book.


2.5.6.3 Carbon Arc Fade-Ometer�

Carbon arc devices generally use two lamps (twinarc). The flame carbon arc is open or enclosed.Enclosed Carbon Arc (ECA) is encased in a borosil-icate glass cover that acts as a filter for low-wave-length radiation. The spectral emission of the flamecarbon arc, a significant amount of which is below300 nm, bears little resemblance to sunlight. The twostrong emission bands of an enclosed carbon arcpeak at 358 and 386 nm and are much more intensethan natural sunlight. Therefore, carbon arc testingwill have a weaker (than actual outdoor) effect onmaterials that absorb only short-wavelength radia-tion. In addition, ECA results will have a stronger(than actual outdoor) effect on materials that absorblong-wavelength UV and visible light.7

Sunshine Carbon Arc provides a better match tonatural sunlight than ECA at longer wavelengths.However, Sunshine Carbon Arc provides moreradiation at wavelengths below 300 nm than naturalsunlight.7

Due to the fact that some materials absorbprimarily short wavelengths and some materialsabsorb primarily longer wavelengths, carbon-arclight sources can distort the relative light stability oftested materials, especially when compared tosamples exposed to actual solar radiation.7

“While good correlation with outdoor exposureshas been reported for some materials whose weath-ering mechanisms are appropriate for these limitedspectrum sources, this technology has largely beenreplaced with fluorescent UVor xenon arc systems.”

Carbon arc testing continues to be used to testmaterial durability in some applications.7

2.5.6.4 SEPAP

The SEPAP 12-24 (SEPAP comes from French:Service d’Etude du Photovieillissement Accelere desPolymeres) exposure equipment is a tool primarilyused by researchers studying photochemistry.Samples being exposed are very carefully controlled.A rotating carousel is used for the test specimens toensure uniformity of the temperature and irradianceat the exposed specimen’s surface. The incident lightemitted by four “medium pressure” mercury arcs andfiltered by the borosilicate envelops that emit discreteradiation at 290, 313, 365, 405, 436, 547 and 579 nm.The carousel and lamps are shown in Fig. 2.45. This

Figure 2.45 The rotating sample carousel is posi-tioned in the middle of four medium pressure mercuryarc lamps.10 For color version of this figure, the readeris referred to the online version of this book.

Figure 2.46 Spectral Power Distributionof lamps in a SEPAP 12-24 instrument.


lamp/envelop output is shown in Fig. 2.46. Thetemperature of the exposed surface is maintained andcontrolled at 60� ˚C; in SEPAP 12-24. No externalwater is usedduring exposure, butwatermaybepresentin the matrix that is produced through the decomposi-tion of primary hydroperoxides. The aggravating effectof water could be evaluated through post photochem-ical immersion in neutral water at 60 ˚C.SEPAP is primarily employed to examine the

photodegradation mechanisms. Spectroscopic anal-ysis of SEPAP exposed coupons is common as it isa researcher’s tool. For example, infrared spectros-copy may look for changes in the chemistry of thepolymers, such as disappearance of carbonyl groups.SEPAP 12-24H includes a humidity option to theexposure environment.

2.5.7 Ozone Testing

Ozone testing is often done on elastomers and itoften leads to embrittlement and cracking as shownin Fig. 2.47. It is done by exposing test pieces such asO-rings or hose in an ozone chamber. These cham-bers generally have of several features:

1. Ozone-Generating Module generating ozoneconcentrations typically in the range of0.1e5.0 ppm

2. Ozone-Monitoring Module that works togetherwith the generating module to createa controlled ozone concentration

3. Test Chamber Module that is completelysealed and constructed of stainless steel andozone compatible seals

4. Ozone Scrubber to eliminate ozone from labo-ratory air as an exhaust hood is not necessary

5. Safety Interlocks Module

Several standards exist that cover ozone exposuretesting:

� ASTM D1149: Standard Test Method forRubber DeteriorationdSurface Ozone Crackingin a Chamber

� ASTM D1171: Standard Test Method for RubberDeteriorationdSurface Ozone Cracking Outdoorsor Chamber (Triangular Specimens)

� ASTM D518: Standard Test Method for RubberDeteriorationdSurface Cracking

� ASTM D380: Standard Test Methods for RubberHose

� SAE J517: Hydraulic Hose

� SAE J1401: Road Vehicle Hydraulic Brake HoseAssemblies for Use With Nonpetroleum-BaseHydraulic Fluids

� FMVSS 106: Federal Motor Vehicle Safety Stan-dard No. 106; Brake hoses

� MIL-STD-202G

� MIL-STD-1344

Note: Q-Lab, the Q-Lab logo, QUV, Q-SUN,QCT, Q-TRAC, Q-RACK, AUTOCAL, SOLAREYE, Q-PANEL, and the Q-shaped hole are regis-tered trademarks of Q-Lab Corporation.

References

1. Jellinek HHG. Reactions of linear polymers withnitrogen dioxide and sulfur dioxide. Text Res J1973;43:557e60.

2. McKeen L. The effect of sterilization on plasticsand elastomers. Elsevier; 2012.

3. Yang H, Zhu S, Pan N. Studying the mechanismsof titanium dioxide as ultraviolet-blockingadditive for films and fabrics by an improvedscheme. J Appl Polym Sci 2004;92:3201e10.

4. Jervis DA. Optical brighteners: improving thecolour of plastics. Plast Addit Compound; 2003:42e6.

5. Robinson J, Linder A, Gemmel A. Comparisonof standard UV test methods for the ageing of

Figure 2.47 Cracking in an elastomer O-ring causedby Ozone.10


cables, International Wire & Cable Symposium.Proceedings of the 60th IWCS conference; 2011.p. 329e337.

6. Azuma Y, Takeda H, Watanabe S, Nakatani H.Outdoor and accelerated weathering tests forpolypropylene and polypropylene/talc com-posites: a comparative study of their weather-ing behavior. Polym Degrad Stab 2009;94:2267e74.

7. Laboratory weathering testing. Atlas MaterialTesting Solutions; 2005.

8. Wypych G. Handbook of material weathering.3rd ed. ChemTec Publishing; 2003.

9. Accelerated weathering by QUV�. PlasticsTechnology Laboratory; 2005.

10. Photograph from Wikimedia.11. Choice of lamps for the QUV�. Q-Panel� Lab

Products; 2005.


3 Introduction to Plastic Properties

3.1 Introduction to the Physical,Mechanical, and ThermalProperties of Plastics andElastomers

Weathering processes can have an effect on theproperties of plastics and elastomers that are used inexterior applications. In some cases, the propertiesmay change so much that the plastics may fail duringnormal use. The properties affected range fromappearance properties such as color or haze tomechanical properties relating to strength or flexi-bility. The data chapters of this book deal with thosedetails of property change. This chapter summarizeshow those properties are measured and in many caseswhy they are important. The properties are groupedinto three groups: appearance, mechanical andthermal. The tests cover a wide range of propertiesbecause the plastics used may be molded or extrudedproducts, such as toys, automotive parts, tools, siding,fencing, sheds, etc. They might be films such aspackaging, pool and spa covers, or filaments such asclothing, rope and thread.

3.2 Appearance Properties

Change in appearance often is the first thing noticedby consumers. Fading and chalking, yellowing andhaze development are examples; changes of theseproperties can be quantified by instrumental tests.

3.2.1 Color

Color perception and measurement is a complexsubject. It will be just briefly discussed here, butthere are many references in greater detail.1,2 Threethings are required to see: color, a light source, andobject and an observer.

A light source is a real physical source of light,such as the sun or any type of light bulb. Anilluminant is a plot of the relative energy vs. wave-length and these are different for various light sources.

Several common illuminants used in color scienceare:

A¼ incandescentC¼ average daylightD65¼ noon daylightF2¼ cool white fluorescentU30¼UltralumeBy using illuminant to describe a light source the

course is quantified and standardized.The object interacts with the incident light. It can

absorb or reflect light. The reflection can be specular(like a mirror) or diffuse. Diffuse reflection is whereincoming light is reflected in a broad range ofdirections. Some light may pass through as trans-mitted light. The amount of light reflected or trans-mitted can be quantified.

The observer may be the human eye. The eye haslight sensors in it called cones, some sense red, somegreen and some blue. Luminosity is the relativesensitivity of the eye to the various wavelengths oflight. The observer needs to be quantified. Thestandard observer was experimentally derived toquantify the sensitivity of the average human eye tored, green and blue light. The standard observer wascalled International Commission on Illumination(CIE) 1931 2�, because the work was done by CIE in1931 and used a 2� field of view. The work was laterredone in 1964 and used a 10� field of view andbecame the CIE 1964 10� standard observer.

Figure 3.1 shows the mathematical forms thatmimic the response of the human eye to light. Z is theblue cone response, X is the red and Y the green.

When this is all applied to an instrument itbecomes the CIE tristimulus XYZ color scale and iscalculated as follows:

X¼ ! (R or T ) � illuminant factor � X factorof standard observer

Y¼ ! (R or T ) � illuminant factor � Y factorof standard observer

Z¼ ! (R or T ) � illuminant factor � Z factor ofstandard observer

whereR¼% reflectanceT¼% transmittance




Sums are across the spectral range for which theinstrument reads.There are other tristimulus color scales, such as

Hunter L, a, b and CIE L*a*b*, but these can all bemathematically calculated from the XYZ color scale.The advantage of these two scales is that they aremore visually uniform and easy to understand asshown in Fig. 3.2.In a uniform color scale, the differences between

points plotted in the color space correspond tovisual differences between the colors plotted. TheHunter L, a, b color space, pictured Fig. 3.2 isorganized in a cube form. The L-axis runs from topto bottom. The maximum for L is 100, whichwould be a perfect white. The minimum for L

would be zero, which would be black. The “a” and“b” axes have no specific numerical limits. Positive“a” is red. Negative “a” is green. Positive “b” isyellow. Negative “b” is blue. Often, the values ofinterest are changes in color often due to exposureor aging, with the parameters being DL, Daand Db.Hunter Lab color space was developed in the

1950s and 1960s.3 CIE L*a*b* space is similar andwas developed around 1964 but is more popularnow than Hunter Lab color space. As stated before,both are mathematically related to XYZ colorsspace, and the formulas relating the two are different.The formulas that related Hunter L, a, b to CIE

XYZ tristimulus are given in Eqns (3.1)e(3.3).

L ¼ 100

ffiffiffiffiffiY

Yn

r(3.1)

a ¼ Ka

X=Xn � Y=Ynffiffiffiffiffiffiffiffiffiffiffi

Y=Ynp

!(3.2)

b ¼ Kb

Y=Yn � Z=Znffiffiffiffiffiffiffiffiffiffiffi

Y=Ynp

!(3.3)

Where:X, Y and Z are the CIE tristimulus values.Xn, Yn and Zn are the tristimulus values for the

illuminant.Yn is 100.00.Xn and Zn are listed in the tables below.

Figure 3.1 The 2� vs. 10� standardobserver.

Figure 3.2 Visual representation of the Hunter L, A,b color scale.


Ka and Kb are chromaticity coefficients forthe illuminant and are listed in the Tables 3.1 and 3.2.

Delta E (dE or dE) is a single number that repre-sents the ‘distance’ between two colors on the colorcoordinate systems.

APHA (American Public Health Association)color is occasionally measured though that test isprimarily aimed at measuring color of clear liquids.The standard is American Society for Testing andMaterials (ASTM) D1209-05(2011) Standard TestMethod for Color of Clear Liquids (platinumecobalt scale). It quantitates a comparison of theintensity of yellow-tinted samples. It is specific to thecolor yellow and is based on dilutions of a 500 ppmplatinum cobalt solution.

3.2.2 Gloss Measurement

Gloss is a measurement of the relative luster orshininess of a film surface. What affects film gloss?Gloss is primarily determined by nature of thematerial and surface smoothness. Smoothness isaffected not only by the product composition but bythe production process. Transparent films have tworeflecting surfaces.

A glossmeter measures specular reflection.Unpolarizedwhite light is concentrated by a condenserlens onto a field aperture, which is located in the focalplane of the source lens. The reflected beam at thesurface is later collected by the receptor lens. Theintensity of the beam is then measured with a photo-detector. The common angles of incidence for glossmeasurement are 20�, 60� and 85�. Low gloss surfacesare recommended to be measured with 85� settings.

The typical standards for gloss measurements are:

� ASTM D2457d08e1 Standard Test Method forSpecular Gloss of Plastic Films and Solid Plastics

� ISO 2813:1994 Paints and varnishesdDetermination of specular gloss of nonmetallicpaint films at 20�, 60� and 85�

� DIN 67,530 Reflectometer as a means for glossassessment of plane surfaces of paint coatingsand plastics

A high gloss requires a smooth surface. Surfaceimperfections may be introduced by the processing.Excessive drawing into the strain-hardening regionwill usually reduce the gloss. Blown film usually hasa lower gloss, since crystallization of the film at thefrost line introduces surface roughness. Rapid crys-tallization of the film by the use of chilled airimpinging on the bubble reduces the size of crystalsand improves the gloss. Extrusion cast film passesthrough chilled rollers after leaving the extruder. Therapid cooling minimizes crystallization and the pol-ished surface of the rollers provides a high-glosssurface. Extrusion cast films have the higher gloss,but the extrusion-blown process produces film ata lower cost. The rheology of the polymer will affectthe surface of the film.

3.2.3 Haze Measurement

Haze is the internal scattering of light and so it isan internal bulk property. Crystallinity, optical

Table 3.1 Parameters Relating Hunter Lab to CIE XYZ, CIE 2 Degree Standard Observer

Illuminant Xn Zn Ka Kb

A 109.83 35.55 185.20 38.40

C 98.04 118.11 175.00 70.00

D65 95.02 108.82 172.30 67.20

F2 98.09 67.53 175.00 52.90

TL 4 101.40 65.90 178.00 52.30

UL 3000 107.99 33.91 183.70 37.50

D50 96.38 82.45 173.51 58.48

D60 95.23 100.86 172.47 64.72

D75 94.96 122.53 172.22 71.30

3: INTRODUCTION TO PLASTIC PROPERTIES 45

defects, “fish eyes”, phase separation of blends,contaminants, gel particles and dispersion ofpigments are structures that increase haze. Hazemakes it difficult to clearly see objects througha film as a result of the interference from randomlyscattered light reaching the viewer in addition tolight coming straight from the object. Smallercrystals provided by a nucleating agent willdecrease haze.The test standards are:

� ASTM D1003d11 Standard Test Method forHaze and Luminous Transmittance of TransparentPlastics

� ISO/DIS14782 PlasticsdDetermination of Hazeof Transparent Materials

3.2.4 Yellowness Index

As plastic materials degrade, especially fromhigh heat, they tend to turn yellow or brown. Ratherthan to measure and report full color change data,a parameter to characterize this change is calledyellowness index (YI). YI is a number calculatedfrom spectrophotometric data that describe the

change in color of a test sample from clear or whitetoward yellow. This is one of the most common testsdone on plastics exposed to sterilization processes.A Hunter Lab color measurement instrument maybe used to measure YI. The illuminant should beD65 for ASTM E313. Illuminant C may be used forother standards. The standard observer function is2� or 10�. Transmittance or reflectance modes maybe used.YI per ASTM method E313 is calculated per

Eqn (3.4):

YI ¼ 100ðCxX � CzZÞ=Y (3.4)

Where:X, Y, and Z are the CIE tristimulus values and the

coefficients depend on the illuminant and observer asindicated in Table 3.3. YI may only be calculated forilluminants D65 and C.YI per ASTM method D1925 is calculated

as follows: for all instruments except UltraScan XE:

YI ¼ 100ð1:274976795X � 1:058398178ZÞ=Yunder C=2� conditions

(3.5)

Table 3.2 Parameters Relating Hunter Lab to CIE XYZ, CIE 10 Degree Standard Observer

Illuminant Xn Zn Ka Kb

A 111.16 35.19 186.30 38.20

C 97.30 116.14 174.30 69.40

D65 94.83 107.38 172.10 66.70

F2 102.13 69.37 178.60 53.60

TL 4 103.82 66.90 180.10 52.70

UL 3000 111.12 35.21 186.30 38.20

D50 96.72 81.45 173.82 58.13

D60 95.21 99.60 172.45 64.28

D75 94.45 120.70 171.76 70.76

Notes: (1) Similar formulas are available for CIE L*a*b*.4

Table 3.3 Tristimulus Coefficients

Coefficient C/2� D65/2� C/10� D65/10�

CX 1.2769 1.2985 1.2871 1.3013

CZ 1.0592 1.1335 1.0781 1.1498


for UltraScan XE:

YI ¼ 100ð1:274641506X � 1:057434092ZÞ=Yunder C=2� conditions

(3.6)

The YI formula is shown in ASTM D1925 as:

YI ¼ 100ð1:28 XCIE � 1:06 ZCIEÞ=YCIEunder C=2� conditions

(3.7)

The tristimulusvaluesofclearair (forCIE illuminantCand the 1931 CIE 2� standard observer) are X¼ 98.041,Y¼ 100.000 and Z¼ 118.103. Using these values, theASTM formula yields YI¼ 0.303 for clear air becausethe factors are truncated to three significant figures. Inorder to set the YI for air equal to 0.0, the constantmultipliers forXCIEandZCIEhavebeenexpandedslightly.The ASTM D1925 method was withdrawn in 1995, butthis formula still provides useful information. This indexis always calculated forC/2�, regardless what illuminantand observer are chosen. The focus of this index was onevaluation of transparent plastics.

3.3 Mechanical Testing ofPlastics

Thedata chapters of this book contain tables andplotsof various mechanical properties of plastics before andafter being exposed to natural or artificial weathering.Many, but not all of these may be as a function oftemperature, strain, humidity etc. This section willsummarize the standard mechanical tests. Details onsome of the more common test methods will follow.

Standard plastics tests are generally specifiedprimarily by two standards organizations. ASTMInternational, originally known as the AmericanSociety for Testing and Materials is one organization;its standards are the well-known ASTM standards.The second organization is the International Organi-zation for Standardization, abbreviated as ISO that isalso well known. These organizations do not specifyjust plastics tests, but they both develop technicalstandards in whatever fields they need them. They areboth well accepted, but unfortunately they do notalways agree exactly. While there is often one-to-onecorrelation of ASTM and ISO standards, they maydiffer in procedure and conditions, which may lead toslightly different measures. While reported values aresimilar, they are rarely exactly the same. Thesestandard tests are listed in Tables 3.4e3.9.

Manyplastics familieshave their ownASTMandISOguidelines for testing. These guidelines provide standardtesting procedures including sample preparation andoften define the subclassification of the plastic products.Some of these standards are given in Table 3.10.

3.3.1 Tensile Properties

Tensile testing is performed by elongating a spec-imen and measuring the load carried by the spec-imen. This is done using a test machine known as anInstron Universal Materials Testing Machine. Fromknowledge of the specimen dimensions, the load anddeflection data can be translated into a stressestraincurve. Avariety of tensile properties can be extractedfrom the stressestrain curve. The standard tests are:

� ASTM D638-03dStandard Test Method forTensile Properties of Plastics

� ISO 527-1:1993 PlasticsdDetermination oftensile propertiesdPart 1: general principles

� ISO 527-2:1993 PlasticsdDetermination oftensile propertiesdPart 2: test conditions formoulding and extrusion plastics

� ISO 37 Rubber, vulcanized or thermoplasticdDetermination of tensile stressestrain properties

� ASTM D412-98a(2002)e1dStandard TestMethods for Vulcanized Rubber and Thermo-plastic ElastomersdTension

The additional standard tests for film are differentfrom the general molded plastics:

� ASTM D882d10 (Standard Test Method forTensile Properties of Thin Plastic Sheeting)

� ISO527-3 (PlasticsdDetermination of tensilepropertiesdPart 3: test conditions for films andsheets)

� JIS K7127:1999 (PlasticsdDetermination oftensile propertiesdPart 3: test conditions for filmsand sheets)

Figure 3.3 shows a picture of an Instron�

Universal Materials Testing Machine and a diagramof the test plaque and details of the test configuration.The sample jaws for film are slightly different thanpictured, and typically have rubber surfaced grips tosecurely hold thin films. The instrument can providea stress vs. strain curve such as that shown in Fig. 3.4.


Analysis of this curve leads to several usefulmechanical measurements.Figure 3.4 has several points on the curve labeled.

These are called as follows:

� “A” is the “proportional limit” which is the end ofthe region in which the resin exhibits linearstressestrain behavior.

� “B” is the “elastic limit” after which the part ispermanently deformed when the strain is removed.

� “C” is the “yield point” after which the materialwill deform without a further increase in strain.

� “D” is the “ultimate strength,” which is themaximum stress on the curve.

� “E” is the “breakpoint”.

Table 3.11 shows how some of the tensilemeasurements are made from the stress vs. straincurve in Fig. 3.4.

Most plastics when tested will show one of thefour basic types of stress vs. strain behavior. Theseare shown in Fig. 3.5. The slopes of the curves andthe actual measures of stress and strain may differ,but as the reader views the multipoint curves in thesubsequent chapters of this book, he will recognizedthese forms. Table 3.12 lists several plastics that fiteach of these behavior types.

3.3.2 Rigidity of Plastics Materials

The rigidity of a plastic is determined by the easewith which the plastic is deformed under load.Modulus is the measure that corresponds to rigidityin plastics. In amorphous plastics at temperatureswell below the glass transition temperature, theentire load is absorbed by bond bending andstretching of the polymers making up the plastic. Thechange in rigidity at the Tg in an amorphous polymeris considerable. The modulus may drop more than

Figure 3.3 Instron universal materials testing machine. Photo courtesy of Instron� Corporation.


three orders of magnitude. Further heating of a low tomoderate uncross-linked plastic past its Tg wouldrapidly cause a drop of the modulus toward zero.However, in a high molecular weight plastic such ascast poly(methyl methacrylate), the polymer chainentanglements would enable the material to maintaina significant rubbery modulus up to its decomposi-tion temperature. Similar maintenance of themodulus above zero is achieved when the polymer iscross-linked. The more the cross-linking present, thehigher is the modulus.

Crystallinity can also restrict molecular movementof the polymer chains above the Tg raising themodulus. The higher the crystallinity, the more rigid isthe polymer. Some polymers tend to melt over a widetemperature range, in which case themodulusmay fallover a range of temperatures leading up to the meltingpointTm.The above effects are summarized in Fig. 3.6.

3.3.3 Shear Properties

Measurement of properties under shear conditionsis described in the standard:

� ASTM D732-02 Standard Test Method for ShearStrength of Plastics by Punch Tool

The primary measures are shear strength and shearmodulus. Shear strength is the maximum loadrequired to completely shear a specimen divided bythe sheared area. Shear modulus is the ratio of shearstress to shear strain.

These tests are often done in an Instron� UniversalMaterials Testing Machine. The sample is typicallya molded sheet that has been cut into a disk. Thediagram of the apparatus used is shown in Fig. 3.7 fora molded sample and Fig. 3.8 for a film sample.

Table 3.4 Standard Mechanical Tests

Measurement ASTM ISO

Apparent Bending Modulus ASTM D747 e

Coefficient of Friction ASTM D1894 e

Compressive Modulus ASTM D695 ISO 604

Compressive Strength ASTM D695 ISO 604

Deformation Under Load ASTM D621 e

Flexural Creep ASTM D2990 e

Flexural Creep Modulus e ISO 6602

Flexural Modulus ASTM D790 ISO 178

Flexural Strength ASTM D790 ISO 178

Flexural Strength at Break ASTM D790 e

Flexural Strength at Yield ASTM D790 e

Nominal Tensile Strain at Break e ISO 527-1, -2

Poisson’s Ratio ASTM E132 e

Shear Modulus ASTM D732 e

Shear Strength ASTM D732 e

Tensile Creep Modulus e ISO 527-1, -2

Tensile Elongation at Break ASTM D638 ISO 527-1, -2

Tensile Elongation at Yield ASTM D638 ISO 527-1, -2

Tensile Modulus ASTM D638 ISO 527-1, -2

Tensile Strength ASTM D638 e

Tensile Strength at Break ASTM D638 ISO 527-1, -2

Tensile Strength at Yield ASTM D638 ISO 527-1, -2

Tensile Strength, Ultimate ASTM D638 ISO 527-1, -2


Table 3.7 Standard Hardness Tests


Ball Indentation Hardness e ISO 2039-1

Durometer (Shore) Hardness ASTM D2240 ISO 868

Rockwell Hardness ASTM D785 ISO 2039-2

Table 3.6 Standard Impact Tests


Charpy Notched Impact Strength ASTM D256 ISO 179

Charpy Unnotched Impact Strength e ISO 179

Drop Impact Resistance ASTM D4226 e

Gardner Impact ASTM D5420 & D5628 e

Instrumented Dart Impact ASTM D3763 e

Multiaxial Instrumented Impact Energy e ISO 6603-2MAII

Multiaxial Instrumented Impact PeakForce

e ISO 6603-2MAII

Notched Izod-Impact Strength ASTM D256 ISO 180

Reverse Notch Izod-Impact Strength ASTM D256 e

Tensile Impact Strength ASTM D1822 ISO 8256

Unnotched Izod-Impact Strength ASTM D256 ISO 180

Table 3.5 Standard Elastomer Tests


Compression Set ASTM D395 ISO 37

Elongation at Break ASTM D412 e

Elongation at Yield ASTM D412 e

Elongation Set After Break ASTM D412 e

Tear Strength ASTM D624 ISO 34-1

Tear Strength, Split ASTM D412 e

Tensile Set ASTM D412 e

Tensile Strength at Break ASTM D412 ISO 37

Tensile Strength at Yield ASTM D412 ISO 37

Tensile Stress at 100% ASTM D412 ISO 37



Tensile Stress at 50% ASTM D412 e


The test specimen, disk or plaque, is placed ina clamp such that its upper and lower surfaces aresecurely supported. Specimen thickness should bebetween 0.127 mm and 12.7 mm (0.005 in. and0.5 in.). A punch-type shear tool with a 25.4 mm(1 in.) diameter is bolted to the specimen througha hole drilled in the center and a load is applied to thepunch. The shear strength is calculated as themaximum force encountered during the test dividedby the area of the sheared edge (circumference of thepunched circle multiplied by the specimen thickness,as indicated by the dotted line in Fig. 3.7).

Referring to Fig. 3.9 the Shear strength is calcu-lated by Eqn (3.8).

Shear strength�dyne=cm2

� ¼ F

Acs(3.8)

Where:F¼ load required to puncture the filmAcs¼ the cross-sectional area of the edge of film

located in the path of the cylindrical hole ofthe film holder (2pR� film thickness).

Division by Acs normalizes the data for differencesin thickness from film to film.

Energy to shear (DEs) per unit volume is calcu-lated by Eqn (3.9).

DEs

�erg=cm3

� ¼ AUC

Vc(3.9)

Where:AUC¼ the area under the load vs. displacement

curveVc¼ volume of the film in the die cavity

Table 3.9 Standard Thermal Tests

Thermal ASTM ISO

Brittleness Temperature ASTM D746 ISO 812 & ISO 974

Coefficient of Linear Thermal Expansion(CLTE)

ASTM D696 & ASTM E831 ISO 11359-1, -2

HDT (Heat Deflection Temperature) at8.0 MPa

e ISO 75 method C

HDT at 1.80 MPa ASTM D648 ISO 75 method A

HDT 0.45 MPa ASTM D648 ISO 75 method B

Ductile/Brittle Transition Temperature e ISO 6603-2 Ductile brittle

Glass Transition Temperature ASTM E1356 e

Melting Temperature (DSC) e ISO 3146

Specific Heat ASTM C351 e

Thermal Conductivity ASTM C177 ISO 8302

Vicat Softening Temperature ASTM D1525 ISO 306

Melt Flow Rate/Melt Flow Index ASTM D1238 ISO 1133

Table 3.8 Standard Electrical Tests

Electrical ASTM ISO

Dielectric Constant ASTM D150 IEC 60250

Dielectric Strength ASTM D149 IEC 60243-1

Dissipation Factor ASTM D150 IEC 60250

Surface Resistivity ASTM D257 IEC 60093

Volume Resistivity ASTM D257 IEC 60093


Table 3.10 ISO and ATSM Standards for Common Polymer Families

Polymer Family ISO Standardsa ASTM Standards

Acrylonitrile-Butadiene-Styrene Resin (ABS)

DIS 2580e1&2: 2003 D4673e02

Styrene-Acrylonitrile Resin(SAN)

4894e1&2: 1997 D4203e07

Polystyrene (PS) 1622e1&2: 1994 D4549e03

Polystyrene, Impact (PS-I) 2897e1&2: 2003 D4549e03

Polypropylene (PP) 1873e1&2: 1997 D4101e06bD5857e05a

Polyethylene (PE) 1872e1&2: 2007 D4976e06

Polyvinyl Chloride,Plasticized (PVC-P)

2898e1&2: 1997 D2287e96

Polyvinyl Chloride,Unplasticized (PVC-U)

1163e1&2: 1995 D1784e06a

Polymethylmethacrylate(PMMA)

8257e1&2: 2001 D788e06

Polycarbonate (PC) 7391e1&2: 2006 D3935e02

Acetals (POM) 9988e1&2: 2006 D6778e06

Polyamides (PA) 1874e1&2: 2006 D4066e01a

Thermoplastic Polyester 7792e1&2: 1997 D5927e03

Polyketone (PK) 15526e1&2: 2000 D5990e00

Polyphenylether (PPE,PPO)

15103e1&2: 2000 D4349e96

Thermoplastic PolyesterElastomer

14910e1&2: 1997 D6835e02

E-CTFE e D3275e06

Poly(Vinylidene Fluoride)(PVDF)

e D3222e05

Polytetrafluoroethylene(PTFE)

e D4894e04

Ethylene-TetrafluoroethyleneCopolymer (ETFE)

e D3159e06

Perfluoroalkoxy (PFA) e D3307e06

Tetrafluoroethylene-HexafluoropropyleneCopolymer (FEP)

e D2116e02

aPart 1 of each ISO material standard addresses the "designatory properties" and part 2 describes specific tests, testspecimens, and test conditions.


Figure 3.4 Typical stressestrain curve showing some important measurement points.

Table 3.11 Tensile Properties Determined from a StresseStrain Curve as per ASTM D638

Property Definition

Tensile Elongationat Break

Tensile elongation corresponding to the point of rupture, “J” in Fig. 3.4

Tensile Elongationat Yield

Tensile elongation corresponding to the yield (an increase in strain doesnot result in an increase in stress), “G” in Fig. 3.4

Tensile Strength atBreak

Tensile stress corresponding to the point of rupture, “K” In Fig. 3.4

Tensile Strength atYield

Tensile stress corresponding to the yield point (an increase in strain doesnot result in an increase in stress), “F” in Fig. 3.4

Tensile Strength Tensile stress at a specified elongation

Tensile Strength,Ultimate

The highest tensile stress a material can support before failing, “H” inFig. 3.4

Tensile Modulus The ratio of tensile stress to tensile strain of a material in the elastic region(from no strain to point “B” in Fig. 3.4) of a stressestrain curve. A "tangent"tensile modulus value is the slope of the elastic region of the stressestraincurve and is also known as Young’s modulus, or the modulus of Elasticity.A “secant” tensile modulus value is the slope of a line connecting the pointof zero strain to a point on the stressestrain curve at a specified strain


3.3.4 Flexural Properties

The measurement of flexural properties isdescribed in the standards:

� ASTM D790-03 Standard Test Methods for Flex-ural Properties of Unreinforced and ReinforcedPlastics and Electrical Insulating Materials

� ISO 178:2001 PlasticsdDetermination of flexuralproperties

A test specimen is held as a simply supportedbeam and is subjected to three-point bending asshown in Fig. 3.10. Typically an Instron� is used.Maximum stress and strain occur at the underside ofthe test specimen, directly under the applied force.The preferred test specimen is 80 mm long, 10 mmwide and 4 mm thick. Other specimens may be usedif the length to thickness ratio is equal to 20.

3.3.5 Puncture and ImpactProperties

The resistance of packaging film to puncture isa property of interest to users. There are severalcommon tests used to evaluate puncture resistance.

3.3.5.1 High-Speed Puncture Test

The high-speed puncture test is commonly ASTMD7192-08 High Speed Puncture Properties of PlasticFilm Using Load and Displacement Sensors. Aschematic of test cell that is used in an Instron type ofmachine is shown in Fig. 3.11. The high-speedpuncture test setup consists of a hydraulic actuator(the drive system), puncture probe (or tup), circularclamp, load-sensing device, a set of controllers, dataacquisition board and a computer to control, measureand report.

Figure 3.5 The range of stress vs. strain behaviors.

Table 3.12 Examples of Tensile Responses Exhibited by Various Plastics

Behavior Examples

Brittle Polystyrene, acrylics, SAN, highly reinforced material

Stiff and Strong ABS, polycarbonate, polyamides, highly filled resin

Stiff and Tough Impact modified polyamides, impact polystyrene

Soft and Tough Elastomers, low density


Figure 3.7 Apparatus used for shear property measurements on molded samples.

Figure 3.6 Schematic illustration of dependence of the modulus of a polymer on a variety of factors, where A isan amorphous polymer of moderate molecular weight; B is of such a high molecular weight that entanglementsinhibit flow; C is lightly cross-linked; D is highly cross-linked; E some crystallinity; and F higher crystallinity.


A typical plot of data acquired in this type ofmeasurement is load vs. displacement as shown inFig. 3.12.5 Testing is often done at various impactvelocities, and the recommended speeds in the test

standard are 2.5, 25, 125, 200 and 250 m/min (0.137,1.367, 6.835, 10.936 and 13.670 ft/s).The primary parameters of interest are the

displacement of the probe from initial contact topuncture of the film, the area under the curve andpeak load. From this data, elongation to puncture,puncture strength and energy to puncture may becalculated. Elongation to puncture (ep) is calculatedby Eqn (3.10).

epð%Þ ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiðR2 þ D2Þ

p� R

R� 100 (3.10)

Where:R¼ the radius of the film exposed in the cylin-

drical hole of the film holderD¼ displacement of the probe from point of

contact to point of film puncture.Puncture strength is calculated by Eqn (3.11).

Puncture strength�dyne=cm2

� ¼ F

Acs(3.11)

Where:F¼ load required to puncture the filmAcs¼ the cross-sectional area of the edge of film

located in the path of the cylindrical hole ofthe film holder (2pR� film thickness).

Figure 3.8 Apparatus used for shear property measurements for film samples.

Figure 3.9 Typical recorded measurements for filmsamples.


Division by Acs normalizes the data for differencesin thickness from film to film.

Energy to puncture (DEp) is calculated byEqn (3.12).

DEp

�erg=cm3

� ¼ AUC

Vc(3.12)

Where:AUC¼ the area under the load vs. displacement

curveVc¼ volume of the film in the die cavity

A similar standard test is ASTM F1306 Slow RatePenetration Resistance of Flexible Barrier Films andLaminates.

3.3.5.2 Drop Dart Impact Test forPlastics Film

A dart impact tester is a simple to use stand-alone, noninstrumented tester, for measuringimpact resistance of film, sheet and laminatedmaterials as per ASTM D1709-09 Standard Test

Figure 3.11 Schematic of the high-speed puncture test sample cell.

Figure 3.10 Principle used for flexural property measurements.


Methods for Impact Resistance of Plastic Film bythe Free-Falling Dart Method (methods A & B). Aschematic of a test machine is shown in Fig. 3.13.The test film is clamped securely in a ring at thebase of the drop tower. The bracket holding theweight is adjusted to the appropriate drop height,and the dart is inserted into the bracket. The dartweight is adjustable with added weights. The dartis released to drop onto the center of the testspecimen. The drop weight and the test result arerecorded. This is a pass/fail test. The “Brucetonstaircase” method is used to analyze this test data.A series of drops are conducted. If a test specimenpasses, the drop weight is increased by one unit. Ifa test specimen fails, the drop weight is decreasedby one unit. The results from these impacts areused to calculate the impact failure weightdthepoint at which 50% of the test specimens will failunder the impact.Depending upon the expected impact strength of

the test sample, either method A or method B ischosen. Test method A specifies a dart with a 38 mm(1.5 in.) diameter dropped from 0.66 m (26 in.) andtest method B specifies a dart with a 51 mm (2 in.)diameter dropped from 1.5 m (60 in.).

3.3.6 Izod Impact Strength andCharpy Impact Strength

The standard tests for Izod impact strength are:

� ISO 180:2000 PlasticsdDetermination of Izodimpact strength

� ASTM D256-06a Standard Test Methods forDetermining the Izod Pendulum Impact Resis-tance of Plastics

The standard tests for Charpy impact strength are:

� ISO 179-1:2000 PlasticsdDetermination ofCharpy impact propertiesdPart 1: non-instru-mented impact test.

Both Izod and Charpy tests are based upona swinging pendulum, such as that shown in Fig. 3.14:Basically, the pendulum is raised to a measured

point, and it is then released. The weighted end of thependulum gains speed as it swings toward a mountedmolded bar of the test plastic. It strikes the bar,breaks it and the pendulum loses energy whilebreaking the plastic bar. Therefore, it does not swingas high. The energy lost by the pendulum is equated

Figure 3.12 Typical load vs. deflection plot obtainedfrom the high-speed puncture test.

Figure 3.13 Schematic of a falling dart test device.


with the energy absorbed by the test specimen duringthe breaking process.

There are different ways to mount the test spec-imen, and there are different specimen sizes andpreparation methods. The different sample mountingconfigurations for the Izod and Charpy tests are

shown in Fig. 3.15. Figure 3.16 shows the details ofthe notch. The sharpness of the bottom of the notchaffects the test result. Table 3.13 shows the differentnotch radii possible.

The impact resistance is usually reported at energyper unit length or per unit area.

Figure 3.14 Pendulum type impact strength tester.

Figure 3.15 Izod and Charpy impact test sample configurations.


3.3.7 Gardner and Falling DartImpact Strength

Another impact strength test that uses gravity isthe Gardner impact or falling dart tests. These aredescribed in the following standards:

� D5420-04 Standard Test Method for Impact Resis-tance of Flat, Rigid Plastic Specimen by Means ofa Striker Impacted by a Falling Weight (GardnerImpact)

� D5628-06 Standard Test Method for Impact Resis-tance of Flat, Rigid Plastic Specimens by Meansof a Falling Dart (Tup or Falling Mass)

� D3763-06 Standard Test Method for High SpeedPuncture Properties of Plastics Using Load andDisplacement Sensors

� ISO 7765-2:1994 Plastics film and sheetingdDetermination of impact resistance by thefree-falling dart methoddPart 2: instrumentedpuncture test

The Gardner test uses a piece of equipment likethat shown in Fig. 3.17. A weight is lifted to a givenheight and it is dropped onto a test plaque. Thefalling dart is based on the same principle, but theweight is free falling rather than guided througha tube as in the Gardner equipment.

Plastic materials, in general are blends ofpolymers with additives and fillers. All the compo-nents may well affect the modulus.In practice, one is basically concerned with the

rigidity of the product and this involves not only themodulus of the material but also the shape and sizeof the product. From the points of view of weightsaving, economics in material and ease ofprocessing, it is an important aim to keep sectionthicknesses at a minimum required to achieveperformance targets. Since flat or singly curvedsurfaces have a minimum rigidity the designer maywish to incorporate domed or other doubly curvedsurfaces or ribbing into the product in order toincrease stiffness. Corrugation can also enhancestiffness but in this case the enhancement varies withposition, being greatest when measured at rightangles to the corrugation.

3.3.8 Tear Properties

It is natural for film users to be concerned abouthow easy or difficult it is to tear film materials.There are two common tests for measuring tearstrength: the Elmendorf Tear Strength (a highspeed test) and the Trouser Tear Strength (a lowspeed test).

Table 3.13 Izod and Charpy Impact Notch RadiusOptions

NotchIzod NotchRadius (mm)

Charpy NotchRadius (mm)

A 0.25 0.25

B 1.00 1.00

C e 0.10

Figure 3.16 Izod and Charpy impact test notchdetail.

Figure 3.17 Gardner impact test apparatus.


3.3.8.1 Elmendorf Tear Strength

The Elmendorf Tear Tester determines the tearingstrength by measuring thework done in tearing througha fixed length of the test specimen. It consists of a sectorpendulum pivoted on antifriction ball bearings ona vertical bracket fixed on a rigid metallic base. The testprinciple is fairly simple; the pendulum is lifted up tocertain height. When released, the pendulum will havea certain potential energy, and at the bottomof the swingthe pendulum tears the specimen and the pendulumloses the energy used to tear the sample. The testmachine is shown in Fig. 3.18. The test standards are:

� ASTM D1922d09 Standard Test Method forPropagation Tear Resistance of Plastic Film andThin Sheeting by Pendulum Method

� ISO 6383-2:1983 PlasticsdFilm and shee-tingdDetermination of tear resistancedPart 2:Elmendorf method

A typical test procedure starts with 10 samplescut from the plastic film in the machine direction and10 samples cut in the transverse direction. A sample ispositioned in the tester and clamped in place. A cuttingknife in the tester is used to create a slit in the samplewhich ends 43 mm from the far edge of the sample. Thependulum is released to propagate the slit through theremaining 43 mm. The energy loss by the pendulum,measuredby themachine, is used tocalculate anaveragetearing force.

There are three standard samples for Elmendorf teartesting. The preferred test sample for plastic films is theconstant-radius sample. This sample providesa constant radius from the start of the tear strengthmeasurementduseful for materials where the tearmay not propagate directly up the sample as intended.Another common sample is a 63 mm� 76 mm rect-angle. For textiles, a modified rectangle adds height onthe ends of the sample to help minimize unraveling ofthe outside edges.

3.3.8.2 Trouser Tear Resistance

The trouser tear measurement measures theaverage force required to propagate a tear ata constant tearing speed across a specimen dividedby the specimen thickness. This is done in a loadframe or tensile test machine, such as an Instron�.The trouser tear sample and tear configuration areshown in Fig. 3.19. The sample is precut as shown.The sample looks like a pair of trousers, hence thename of the test. The tensile machine jaws are set toseparate at a rate of either 200 or 250 mm/min.

The tests standards are:

� ASTMD1938d08 Standard Test Method for Tear-Propagation Resistance (Trouser Tear) of PlasticFilm and Thin Sheeting by a Single-Tear Method

� ISO6383-1 Film and SheetingdDetermination ofTear Resistance Part 1 Trouser Tear Method

Figure 3.18 Elmendorf tear test, sample schematic on left, photo of a commercial machine right. Photo courtesyof Testing Machines Inc. For color version of this figure, the reader is referred to the online version of this book.


3.3.8.3 Toughness

Toughness is complex to define and difficult tounderstand. Tough thermoplastic resins are usuallydescribed as having high elongation to failure orones that require a large amount of energy tocause failure. If the plastics are reinforced thenthey need high strength with low elongation. Formany applications, the resistance to impact is themost important property of a plastic material. It isalso notoriously one of the most difficult toassess.If a rigid polymer is struck a blow at a tempera-

ture well below its glass transition temperature,deformation will be small before break occurs.Nevertheless, because of the high modulus, quitehigh tensile strengths will be recorded. But theenergy required to cause the break will be given bythe area under the stressestrain curve and it will notbe very large. On the other hand, if an amorphouspolymer is struck above the Tg, i.e. in the rubberystate, large extensions are possible before fractureoccurs and, although the tensile strength will bemuch lower, the energy to break (the area under thecurve) will be much more, so that for manypurposes the material will be regarded as tough.A common material performance need is a rigid

plastic with the toughness of rubber. This can beachieved in a number of ways:

1. By the use of a moderately crystalline polymerwith a Tg well below the expected servicetemperature (e.g. polyethylene).

2. By block copolymerization so that one compo-nent of the block copolymer has a Tg wellbelow the expected service temperature range(e.g. polypropylene with small blocks of poly-ethylene or preferably polypropylene withsmall amorphous blocks of ethyleneepropy-lene copolymer).

3. By blending with semicompatible materials thathave aTgwell below theexpected service temper-ature range (e.g. high-impact polystyrene).

4. By the use of a polymer that has effective tran-sitions at or below the expected servicetemperature range and which is able to respondto stress by extensive deformation (e.g.polycarbonates).

5. By plasticization. This in effect reduces the Tgand in the case of nylon, which has absorbedsmall quantities of water, the toughening effectcan be quite substantial.

In terms of a stressestrain curve, a brittlematerial may be considered to be one that breakswithout a yield while a tough material yields to givea substantial energy to break. Keep in mind that ifa material has not broken after being struck simplybecause it yielded to an unrecoverable extent theproduct may still be useless.Toughness is not simply a function of polymer

structure or the mode of stressing. It clearly will alsodepend on the temperature and the rate of striking butmore important still it will depend on the productdesign and method of manufacture.Stress tends to concentrate at defects such as the

presence of notches, sharp angles, holes, voids,particle inclusions or small inserts. Different poly-mers vary in their “notch sensitivity” and this ispresumably a reflection of how close they are to theirtoughebrittle transitions. The aim of the designerand processor must be to reduce such stressconcentration to a minimum.

3.4 Thermal Property Testingof Plastics

The properties of plastic films are affected bytemperature. There are also several thermal proper-ties of a more basic nature than affect films perfor-mance. This section will discuss what thoseproperties are and how they are measured.

Figure 3.19 Trouser tear test sample configuration.


3.4.1 Melt Flow Index

TheMelt Flow Index is a measure of the ease of flowof the melt of a thermoplastic polymer. It is defined asthe weight of polymer in grams flowing in 10 minthrough a die of specific diameter and length by a pres-sure applied by a given weight at a given temperature.The method is given in ASTM D1238 and ISO 1133.The test equipment is diagrammed in Fig. 3.20.

The conditions of the test depend upon the type ofthe polymerdsome of which are shown in Table 3.14.One does not want a temperature so high that thepolymers in the plastic decompose. The melt flow rateis an indirect measure of molecular weight, with highmelt flow rate corresponding to a low molecularweight. Synonymsofmelt flow index aremelt flow rateand melt index, which are commonly abbreviated:MFI, MFR and MI. When the volume of the extrudateis measured, the melt volume rate (MVR) is reported.

3.4.2 Heat DeflectionTemperature

The heat deflection temperature is a measure ofa polymer’s resistance to distortion under a givenload at elevated temperatures. Other terms for thismeasurement include deflection temperature underload, or heat distortion temperature (HDT).

The test is performed using an apparatusdiagrammed in Fig. 3.21. A test bar is molded of

a specific thickness and width. The test sample issubmerged in oil that is gradually heated. The load isapplied to the midpoint of the test bar that is sup-ported near both ends. The temperature at whicha bar of material is deformed by 0.25 mm is recordedas the HDT.

The ASTM test is ASTM D 648 while the analo-gous ISO test is ISO 75. The test using a 1.8 MPaload is performed under ISO 75 method A, while thetest using a 0.46 MPa load is performed under ISO75 method B. Less common is the test using an8 MPa load is performed under ISO 75 method C.

The HDT value obtained for a specific polymergrade will depend on the base resin and on thepresence of reinforcing agents. Deflection tempera-tures of glass fiber or carbon fiber-reinforced engi-neering polymers will often approach the meltingpoint of the base resin.

The HDT test results are a useful measure ofrelative service temperature for a polymer when usedin load-bearing parts. However, the deflectiontemperature test is a short-term test and should not beused alone for a product design. Other factors such asthe time of exposure to elevated temperature, the rateof temperature increase and the part geometry allaffect the performance.

3.4.3 Vicat SofteningTemperature

The Vicat softening temperature is the tempera-ture at which a flat-ended needle penetrates thespecimen to the depth of 1 mm under a specific load.The temperature reflects the point of softening to beexpected when a material is used in an elevatedtemperature application.

A test specimen is placed in the testing appa-ratus such as that diagrammed in Fig. 3.22. Thepenetrating needle rests on its surface. A load of10N or 50N is applied to the specimen. Thespecimen is then lowered into an oil bath at 23 �C.The bath is raised at a rate of 50� or 120 �C/h untilthe needle penetrates 1 mm. The temperature atthat moment is called the Vicat softeningtemperature.

The relevant standards are ISO 306 and ASTMD1525. ISO 306 describes two methods, method Awith a load of 10 N and method B with a load of50 N, each with two possible rates of temperaturerise, 50 �C/h and 120 �C/h. This results in ISO valuesreported as A50, A120, B50 or B120.Figure 3.20 Melt flow index test apparatus.


Table 3.14 Recommended Conditions for Determination of MFR and MVR for Common Materials According toISO and ASTM Guidelines (ex. 190/2.16¼ 190 �C with 2.16 kg Weight)

Plastic/PolymerASTM Standard Conditions

(�C/kg)ISO Standard Conditions

(�C/kg)

Acetals (Copolymer andHomopolymer)

190/2.16, 2.16, 1.05 190/2.16

Acrylics 230/1.2, 230/3.8 230/3.8

Acrylonitrile-Butadiene-Styrene(ABS)

200/5.0, 230/3.8, 220/10 220/10

Acrylonitrile/Butadiene/Styrene/Polycarbonate Blends

230/3.8, 250/1.2, 265/3.8, 265/5.0 e

Cellulose Esters 190/0.325, 190/2.16, 190/21.60,210/2.16

e

Ethylene-ChlorotrifluoroethyleneCopolymer (ECTFE)

271.5/2.16 e

Ethylene-TetrafluoroethyleneCopolymer (ETFE)

297/5.0 e

Nylon 275/0.325, 235/1.0, 235/2.16, 235/5.0, 275/5.0

e

Perfluoro(EthyleneePropylene)Copolymer (FEP)

372/2.16 e

Perfluoroalkoxyalkane (PFA) 372/5.0 e

Polycaprolactone 125/2.16, 80/2.16 e

Polychlorotrifluorethylene (PCTFE) 265/12.5 e

Polyether Sulfone (PES) 380/2.16, 360/10, 343/2.16 e

Polyethylene (PE) 125/0.325, 125/2.16, 250/1.2,190/0.325, 190/2.16, 190/21.60,190/10, 310/12.5

190/2.16, 190/21.6,190/0.325, 190/5

Polycarbonate (PC) 300/1.2 300/1.2

Polypropylene (PP) 230/2.16 230/2.16

Polyphenyl Sulfone (PPSU) 365/5.0, 380/2.16 e

Polystyrene (PS) 200/5.0, 230/1.2, 230/3.8, 190/5.0 200/5

Polysulfone (PSU) 343/2.16, 360/10 e

Polyterephthalate 250/2.16, 210/2.16, 285/2.16 e

Poly(Vinyl Acetal) 150/21.6 e

Poly(Vinylidene Fluoride) (PVF) 230/21.6, 230/5.0, e

Poly(Phenylene Sulfide) (PPS) 315/5.0 e

Styrene Acrylonitrile (SAN) 220/10, 230/10, 230/3.8, 220/10

Styrenic Thermoplastic Elastomer 190/2.16, 200/5.0 e

Thermoplastic Elastomer-Ether-Ester

190/2.16, 220/2.16, 230/2.16,240/2.16, 250/2.16

e

Thermoplastic Elastomers (TEO) 230/2.16 e

Vinylidene Fluoride Copolymers 230/21.6, 230/5.0 e


3.4.4 Melting Point (Tm)

A melting process is also illustrated in Fig. 3.23for the case polyethylene-terephthalate polymer,which is slowly heated through its meltingtemperature, and two other thermal transitionsbesides.

Again, as the melting temperature is reached, anendothermal peak appears because heat must bepreferentially added to the sample to continue thisessentially constant-temperature process. The peak

breadth is primarily related to the size and degree ofperfection of the polymer crystals. This differentialscanning calorimetry (DSC) also provides additionalinformation, the glass transition temperature anda crystallization temperature.

Note that if the process was reversed so that thesample was being cooled from the melt, the plotwould be approximately inverted at the melt pointand glass transition temperature. This corresponds toan exothermal process.

3.4.5 Glass TransitionTemperature, Tg

The glass transition temperature, often called Tg(or “T sub g”), is an important property whenconsidering polymers for a particular end-use. Theglass transition temperature is the temperature,below which the physical properties of plasticschange in a manner similar to those of a glassy orcrystalline state, and above which they behave likerubbery materials. A plastic’s Tg is thetemperature below which molecules have littlerelative mobility. Tg is usually applicable towholly or partially amorphous plastics. A plastic’sproperties can be dramatically different above andbelow its Tg. The next sections show a number ofways to measure or estimate the Tg. Thesemethods will indicate how some of the propertieschange around the Tg. The value of the glasstransition temperature depends on the strain rateand cooling or heating rate, so there cannot be anexact value for Tg.

Figure 3.21 Heat deflectiontemperature (HDT) test apparatus.

Figure 3.22 Vicat softening temperature testapparatus.


3.4.5.1 Mechanical Methodsof Estimating Tg

It is possible to calculate a value for the glass transi-tion temperature by measuring the elastic (or Young’s)modulus of the plastic as a function of the

temperaturedfor example, by using a torsionpendulum. Around Tg there is a large fall in the value ofthemodulus, as shown inFig. 3.24. The frequencyof theoscillation is important, since Tg value depends on thetime allowed for chain segment rotation. While this

Figure 3.23 Melting point estimation from a DSC of polyethylene terephthalate.

Figure 3.24 Tg estimate from an Young’s modulus vs. temperature study.


approach is not commonly used, as there are bettermethods, it does demonstrate one way in which a plas-tic’s physical properties change above and below the Tg.

A more common mechanical method is dynamicmechanical thermal analysis (DMTA). DMTA is alsocalled dynamic mechanical analysis or dynamicthermomechanical analysis. An oscillating force isapplied to a sample of material and the resultingdisplacement of the sample is measured. From this,the stiffness of the sample can be determined, and thesample modulus can be calculated. A plot of lossmodulus as a function of temperature showsa maximum at Tg, as shown in Fig. 3.25. Figure 3.25shows a series of blends of high-impact styrene andpolyphenylene oxide (PPO). As the amount of PPOis increased the Tg increases. The single Tg indicatesthat these blends are miscible.

3.4.5.2 Thermal Mechanical Analysis

This method of measuring glass transitiontemperature measures the extension (change inlength) of a piece of film as the temperature is raised.The advantage of this technique is that is can be doneon a small films sample. The film piece is usually atleast 10 mm thick, 2 mm wide and 15e20 mm long.The equipment is a thermomechanical analyzer suchas a Perkin Elmer thermal mechanical analysis

(TMA)-7 with a film fixture. It is run in extensionmode. A 30 mN load is put on the film and thetemperature is slowly raised at a uniform rate and theextension is measured. Extension is plotted vstemperature as shown in Fig. 3.26. Two tangent linesare draw as shown and the intersection of these twolines is the glass transition temperature. Usually, thepoints at which the tangent lines part from themeasurements, TA and TB, gives a glass transitionrange that may be reported.

3.4.5.3 Thermal Methods ofEstimating Tg

Thermal methods of measuring Tg are based ondifferential scanning calorimetry, commonlycalled DSC. In DSC, the thermal properties ofa sample are compared against a standard refer-ence material, typically inorganic, which has notransitions such as a melting point in thetemperature range of interest. A common refer-ence material is powdered alumina. The sampleand reference are each contained in a smallholder within an adiabatic enclosure, as illus-trated in Fig. 3.27.

The temperature of each holder is monitored bya thermocouple and heat can be supplied electricallyto each holder to keep the temperature of the two

Figure 3.25 Tg estimate from dynamic mechanical thermal analysis (DMTA) study.


Figure 3.26 Generic TMA plot used to determine glass transition temperature.

Figure 3.27 Diagram of a DSC sampleand a reference cell.

Figure 3.28 Schematic of a DSC showing a Tg.


equal. The difference in the amount of heat requiredto maintain equal temperature is recorded. A plotis recorded of the difference in energy suppliedagainst the average temperature. As the temperatureis slowly increased, thermal transitions may beidentified.

The glass transition process is illustrated in theFig. 3.28 for a glassy polymer that does notcrystallize and is being slowly heated from below Tg.

Here, the drop marked Tg at its midpointrepresents the increase in energy supplied to thesample to maintain it at the same temperature as thereference material, due to the relatively rapidincrease in the heat capacity of the sample as itstemperature is raised through Tg. The addition of heatenergy corresponds to this endothermal direction.

The specific heat or specific heat capacity, Cp, canbe measured using DSC. It can change dramaticallyat the Tg, as shown in Fig. 3.29. The value of Tg

depends on the heating or cooling rate of the calo-rimetry experiment.

References

1. Malacara Daniel. Color vision and colorimetry:Theory and applications. 2nd ed. Society ofPhoto Optical; January 15, 2011.

2. Arthur Broadbent D. Colorimetry, methods,encyclopedia of spectroscopy and spectrometry.2009. p. 372e379.

3. Applications Note. Hunter L, a, b color space,Insight on Color 2008; 8(9).

4. Applications Note. CIE L*a*b* color space,Insight on Color 2008; 8(7).

5. Radebaugh GW, Murtha JL, Julian TN, Bondi JN.Methods for evaluating the puncture and shearproperties of pharmaceutical polymeric films. IntJ Pharm 1988;45:39e46.

Figure 3.29 Tg estimate from the change in specific heat capacity vs. temperature for a commercial polysulfone.


4 Styrenic Plastics

4.1 Styrenic Plastics

This chapter on styrenic plastics covers a broadclass of polymeric materials of which an importantpart is styrene. Styrene, also known as vinyl benzene,is an organic compound with the chemical formulaC6H5CH]CH2. Its structure is shown in Fig. 4.1.

It is used as a monomer to make plastics such aspolystyrene, acrylonitrile-butadiene-styrene (ABS),styreneeacrylonitrile (SAN), and other polymersdiscussed in this chapter.

4.2 ABS Copolymer

ABS is a common thermoplastic used to makelight, rigid molded products.

SAN copolymers have been available since the1940s, and while its increased toughness over poly-styrene made it suitable for many applications, itslimitations led to the introduction of a rubber, buta-diene, as a third monomer producing the range ofmaterials popularly referred to as ABS plastics.These became available in the 1950s. The avail-ability of these plastics and the ease of processing ledABS to become one of the most popular engineeringpolymers.

The chemical structures of the monomers are shownin Fig. 4.2. The proportions of the monomers typicallyrange from 15% to 35% acrylonitrile, 5% to30% butadiene and 40% to 60% styrene. It can befound as a graft copolymer, in which the SAN poly-mer is formed in a polymerization system in thepresence of polybutadiene rubber latex; the finalproduct is a complex mixture consisting of SAN

copolymer, a graft polymer of SAN and polybutadieneand some free polybutadiene rubber.

Weathering Properties: When ABS is used forextended periods in outdoor locations or underfluorescent light, discoloration, typically yellowing,and degradation of properties, particularly impactstrength, will occur. The main cause of weathering-related ABS problems is light-induced photooxida-tion of the polybutadiene component. See Fig. 4.3 fordetails on these chemical reactions. This leads tocross-linking of the polybutadiene rubbery phase,which reduces its elastomeric properties, so thecontribution of the rubber to improved impactstrength is reduced. This type of degradation isrestricted to surface layers, typically the outer 50 mm(2 mils). The yellowing is attributed primarily to theSAN phase in ABS.

Stabilization1: Because of its butadiene compo-nent, ABS requires ultraviolet (UV) stabilizers.Synergistic combinations of UV absorbers (UVAs)are often used.

� UVA: such as benzophenones (example: 2-hydroxy-4-octyloxybenzophenone) or benzotriazoles(example: 2-(2H-benzotriazol-2-yl)-p-cresol) andhindered amine stabilizers (example: 1,3,5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl-(1,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-)

� Phenolic antioxidants: such as ethylene-bis(oxy-ethylene)-bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate)

� Phosphites: such as trinonylphenol phosphiteFigure 4.1 Chemical structure of styrene.

Figure 4.2 Chemical structures of acrylonitrile-butadiene-styrene (ABS) raw materials.




Manufacturers and trade names include:SABIC Innovative Polymers Cycolac�; INEOSLustran� and Novodur�; and Perrite Ronfalin�,Dow Magnum and BASF AG Terulan�.Data for ABS plastics are found in Tables 4.1e4.6

and Figs 4.4e4.38.

4.3 Polystyrene

Polystyrene is the simplest plastic based onstyrene. Its structure is shown in Fig. 4.39. Its CASnumber is 9003-53-6.Pure solid polystyrene is a colorless hard plastic

with limited flexibility. Polystyrene can be trans-parent or can be made in various colors. It iseconomical and is used for producing plastic modelassembly kits, plastic cutlery, CD “jewel” cases, andmany other objects where a fairly rigid, economicalplastic is desired.

Polystyrene’s most common use, however, is asexpanded polystyrene (EPS). EPS is produced froma mixture of about 5e10% gaseous blowing agent(most commonly pentane or carbon dioxide) and

Figure 4.3 Photochemistry of ABS degradation.

Table 4.1 Surface and Appearance Changes inWhite ABS as a Result of Outdoor Weathering inFlorida2

DE Color 12.8

Yellowness Index 35.6a

DYellowness Index 21a

Yellowness Index 30.7b

DYellowness Index 18.8b

Whiteness Index �16.7

DWhiteness Index �61.1

Notes: (1) 45� south. (2) 365 days.aTest method: ASTM D1925-70.bTest method: ASTM E313-73.


Table 4.2 Property Changes in ABS as a Result of Outdoor Weathering in Ludwigshafen, Germany3,4

Exposure Conditions

Exposure Time (Days) 15 30 45 60

Property Values after Exposure

Notched Impact Strength (kJ/m2) 10.4 11.3 12.2 10.2

Impact Strength Retained (%) 99.2 98.4 96.8 95.3

Notes: (1) 45� south; for notched impact strength notched side exposed to light, struck on unexposed side, thus subjectingexposed side to dynamic loading.

Table 4.3 Accelerated Indoor Fluorescent Light Exposure of Sabic Innovative Plastics Cycolac� KJB ABS5,6

Exposure Conditions

Exposure Time (Days) 30 91 182 274 365

Surface and Appearance

DE Color Change 0.07 0.26 0.44 0.77 1.18

Notes: (1) 1.83 m from four, 40 W fluorescent lights. (2) Test method: CIE lab color scale.

Table 4.4 Influence of the Accelerated Weathering on Physical Properties of ABS (First Reprocessing)7

QUV�

Time (h)Time Correspondence

(Years)Modulus of Elasticity

(N mm-2)Tensile Strength

(N mm-2)

0 0 2652� 75 48.6� 0.3

50 1.8 2391� 36 47.0� 0.3

120 4.4 2431� 68 26.1� 4.3

215 7.9 2462� 58 19.5� 3.4

430 15.8 2497� 41 13.9� 2.5

600 22.1 2461� 19 15.7� 3.4

Table 4.5 Influence of the Accelerated Weathering on Physical Properties of ABS (Fifth Reprocessing-Recycled)7

QUV�



(N mmL2)Tensile Strength

(N mmL2)

0 0 2563� 69 49.0� 0.3

50 1.8 2476� 50 39.5� 10

120 4.4 2410� 50 17.7� 4.9

260 9.6 2513� 36 20.3� 2.7

4: STYRENIC PLASTICS 73

90e95% polystyrene by weight. The solid plasticbeads are expanded into foam using heat (usuallysteam). The heating is carried out in a large vesselholding 200e2000 l. An agitator is used to keep thebeads from fusing together. The expanded beads arelighter than the unexpanded beads so they are forced tothe top of the vessel and removed. This expansionprocess lowers the densities of the beads to 3% of theiroriginal value and yields a smooth-skinned closed cellstructure. Next, the pre-expanded beads are usually“aged” for at least 24 h in mesh storage silos. Thisallows air to diffuse into the beads, cooling them andmaking them harder. These expanded beads areexcellent for detailed molding. Extruded polystyrene,

which is different from EPS, is commonly known bythe trade name Styrofoam�. All these foams are not ofinterest in this book.Two general forms of polystyrene are

� General purpose polystyrene (PS or GPPS)

� High-impact polystyrene (HIPS)

One of the most important plastics is HIPS. This isa polystyrene matrix that is imbedded with an impactmodifier, which is basically a rubber-like polymersuch as polybutadiene. This is shown in Fig. 4.40.High-impact grades typically contain in the range of6e12% elastomers and medium-impact gradescontain about 2e5%.

Table 4.6 Influence of the Accelerated Weathering on Physical Properties of ABS (Tenth Reprocessing-Recycled)7

QUV�



(N mmL2)Tensile Strength

(N mmL2)

0 0 2492� 61 49.8� 0.4

50 1.8 2386� 94 24.8� 9.7

120 4.4 2478� 23 22.7� 3.4

220 8.1 2500� 71 13.9� 4.2

Figure 4.4 Changes in material characteristics due to photooxidation of ABS.8 Notes: the depth of the degradedlayer brought about by weathering is of the order of several hundred micrometers. The reaction to photooxidationresults in the generation of a thin yellow layer at the surface; this layer prevents the diffusion and permeation ofoxygen and, in addition, blocks out light. Accordingly, any further photooxidation at the interior of the componentis prevented.


Figure 4.5 Outdoor weath-ering exposure time vs. yel-lowness index of ABS.3

Figure 4.6 Arizona outdoor weath-ering exposure time vs. dart dropimpact strength of ABS.9

Figure 4.7 Arizona outdoor weath-ering exposure time vs. elongationof ABS.9


Figure 4.8 Arizona outdoor weath-ering exposure time vs. tensilestrength at yield of ABS.9

Figure 4.9 Arizona outdoor weath-ering exposure time vs. DE colorchange of ABS.9

Figure 4.10 Arizona, Florida, andOhio outdoor weathering exposuretime vs. dart drop impact strengthof ABS.10


Figure 4.11 Florida outdoorweathering exposure time vs. dartdrop impact strength of ABS.9

Figure 4.12 Florida outdoorweathering exposure time vs. dropweight impact of ABS.2

Figure 4.13 Florida outdoorweathering exposure time vs.DE color change of ABS.9


Figure 4.14 Florida weatheringexposure time vs. chip impactstrength of ABS (White Rovel Cap-stock and Acrylic Capstock).2

Figure 4.15 Florida weatheringexposure time vs. chip impactstrength of ABS (natural resin).2

Figure 4.16 Ohio outdoor weath-ering exposure time vs. DE colorchange of ABS.9


Figure 4.17 Ohio outdoor weath-ering exposure time vs. dart dropimpact strength of ABS.9

Figure 4.18 Okinawa, Japan,outdoor weathering exposure timevs. E color change of ABS.11

Figure 4.19 Okinawa, Japan,outdoor weathering exposure timevs. Dynstat impact strengthretained of ABS.11


Figure 4.20 Okinawa, Japan,outdoor weathering exposure timevs. elongation at break retained ofABS.11

Figure 4.22 West Virginia outdoorweathering exposure time vs.falling dart impact of ABSat �40 �C.12

Figure 4.21 Okinawa, Japan,outdoor weathering exposure timevs. gloss retention of ABS.11


Figure 4.23 West Virginia outdoorweathering exposure time vs.falling dart impact of ABS at23 �C, �25 �C, and �40 �C.12

Figure 4.24 West Virginia outdoorweathering exposure time vs.falling dart impact of ABS at23 �C.12

Figure 4.25 West Virginia outdoorweathering exposure time vs. flex-ural modulus retained of ABS.12


Figure 4.26 West Virginia outdoorweathering exposure time vs. flex-ural strength of UV-Stabilized (LS)ABS at �40 �C and 23 �C.12

Figure 4.27 West Virginia outdoorweathering exposure time vs. flex-ural strength retained of ABS.12

Figure 4.28 West Virginia outdoorweathering exposure time vs. Izodimpact strength retained of ABS.12


Figure 4.29 West Virginia outdoorweathering exposure time vs.tensile strength retained of ABS.12

Figure 4.30 Sunshine Weather-Ometer� exposure time vs. Dyn-stat impact strength retained ofABS.13

Figure 4.31 Sunshine Weather-Ometer� exposure time vs. elonga-tion at break retained of ABS.11


Figure 4.32 Sunshine Weather-Ometer� exposure time vs. glossretained of ABS.13

Figure 4.33 Weather-Ometer�

exposure time vs. impact strengthof ABS.3

Figure 4.34 Xenotest 1200 expo-sure time vs. impact strength ofABS.3


Figure 4.35 Accelerated indoorUV exposure time vs. DE colorchange of ABS.14

Figure 4.36 Yellowness index ofUVA and hindered amine light stabi-lizers-stabilized ABS after outdoorweathering in Switzerland.15

Figure 4.37 Impact strengthretained of ABS as a function ofhours to actual sunshine exposure.16


Weathering Properties: Polystyrene undergoeslight-induced yellowing on exposure to UV light.Photooxidation leads to yellowing, cracking, loss ofmechanical properties, brittleness, increased absor-bance of UV, gel formation, and molecular weightdecrease. Many small molecules such as hydrogen,water, carbon dioxide, ketone, hydroperoxides, ace-tophenone, benzaldehyde, formic acid, acetic acid,and benzoic acid can be produced by this process.The chemical reaction pathways shown in Fig. 4.41are very similar to those shown in Fig. 4.3 forpolybutadiene in Section 4.2 on ABS.Stabilization1:

� UVAs: such as2-hydroxy-4-methoxybenzophenone

� Hindered amine stabilizers: such as 1,3,5-triazine-2,4,6-triamine


� Screeners: such as carbon black, titanium dioxideand zinc oxide

� Thiosynergists: such as didodecyl-3,30-thiodipro-pionate; dioctadecyl 3,30-thiodipropionate

� Optical brighteners: such as 2,20-(2,5-thiophene-diyl)bis(5-tert-butylbenzoxazole).1

Manufacturers and trade names: BASF Poly-styrene and Polystyrol, Dow Chemical Trycite�,and Styron LLC Styron�.Applications and uses:General Purpose: Yogurt, cream, butter, meat

trays, egg cartons, fruit and vegetable trays, as well

Figure 4.38 Influence of pigmentconcentration on the impactstrength retention of ABS speci-mens exposed to weathering.16

Figure 4.39 Chemical structure of polystyrene.

Figure 4.40 Structure of high-impact polystyrene.


Figure 4.41 Photooxidation pathways of polystyrene.

Table 4.7 Mechanical Properties Retained after California and Pennsylvania Outdoor Weathering of LNPEngineering Plastics Glass-Reinforced General Purpose Polystyrene15

Exposure Location Los Angeles, CA Philadelphia, PA

Exposure Time (Days) 91 182 365 730 91 182 365 730

Properties Retained (%)

Tensile Strength 91 85.3 89 91 86 88 94 85

Notched Izod Impact Strength 122 100 100 100

Unnotched Izod Impact Strength 83 83.3 96 87.5

Notes: (1) Carbon black 1%, glass fiber reinforcement 30%. (2) Exposure test method ASTM D1435.


Figure 4.42 Yellowness index afterAtlas Fade-Ometer� exposure ofgeneral purpose polystyrene.11

Figure 4.43 Yellowness indexafter fluorescent lamp exposure ofBASF Polystyrol� general purposepolystyrene.4

Table 4.8 Color Change, DE, after 18 Months of Outdoor Exposure for INEOS NOVA Chemicals Styrosun� HIPSand Other Materials18

Materials Styrosun� 3600 ASA UV-ABS UV-HIPS Filled PP


DE Florida Exposure 5.2 5.4 18.5 19.4 2.2

DE Arizona Exposure 6.5 6.5 25.3 23.7 1.8

DE Kentucky Exposure 5.0 4.9 24.2 22.0 1.6

DE Illinois Exposure 5.8 4.8 26.1 23.1 1.6


Table 4.9 Color Change, DE, after 18 Months of Florida Outdoor Exposure and 3000 h of Accelerated Weath-ering for INEOS NOVA Chemicals Styrosun� HIPS and Other Materials18

ExposureConditions Florida Outdoor Exposure Accelerated Exposure

Exposure Time 18 Months 3000 h

MaterialsStyrosun�

3600 ASAUV-ABS

FilledPP

Styrosun�

3600 ASAUV-ABS

FilledPP


DE 5.2 5.4 18.5 2.2 5.2 1.3 7.5 2.1

Table 4.10 Impact Retention after 3000 h of Accelerated Weathering for INEOS NOVA Chemicals Styrosun�

HIPS and Other Materials18

Materials Styrosun� 3600 Styrosun� 3600 UV-ABS Filled PP

Retention of Energy at Maximum Load

Impact Retention (%) 80.7 102.7 39.1 107.2

Retention of Total Energy


Retention of Maximum Load


Figure 4.44 Yellowness indexafter Fade-Ometer� exposure ofDow Styron� impact and flame-retardant polystyrene and DowStyron� unmodified polystyrene.17


Figure 4.45 Color change, DE,after Florida outdoor exposure ofINEOSNOVAChemicals Styrosun�

HIPS and other materials.18

Figure 4.46 Color change,DE, afterArizona outdoor exposure of INEOSNOVA Chemicals Styrosun� HIPSand other materials.18

Figure 4.47 Color change, DE,after Kentucky outdoor exposure ofINEOSNOVAChemicalsStyrosun�



Figure 4.48 Color change, DE,after Illinois outdoor exposureof INEOS NOVA ChemicalsStyrosun� HIPS and othermaterials.18

Figure 4.49 Impact property reten-tion, energy at maximum load, after3000 h of Atlas Weather-Ometers�

exposure for INEOS NOVA Chemi-cals Styrosun� HIPS and othermaterials.18

Figure 4.50 Impact property reten-tion, total energy,after3000 hofAtlasWeather-Ometers� exposure forINEOS NOVA Chemicals Styrosun�



Figure 4.51 Impact property reten-tion, maximum load, after 3000 hof Atlas Weather-Ometers� expo-sure for INEOS NOVA ChemicalsStyrosun� HIPS and othermaterials.18

Figure 4.52 Impact strength afterxenon arc weathering of HIPS asper ISO 4692-2.19

Figure 4.53 Yellowness indexafter xenon arc weathering ofHIPS as per ISO 4892-2.20


as cakes, croissants, and cookies. Medical andpackaging/disposables, bakery packaging, and largeand small appliances. Medical and packaging/disposables, particularly where clarity is required.

High Impact: Refrigeration accessories, smallappliances, electric lawn and garden equipment,toys, and remote controls.

4.3.1 General PurposePolystyrene

Data for GPPS plastics are found in Table 4.7 andFigs 4.42 and 4.43.

4.3.2 High-Impact Polystyrene

Unmodified HIPS resins usually experiencegreater change from outdoor exposure than GPPSformulations. HIPS resins usually show less changethan resins modified with ignition-resistant chemical

additives.17 Solar radiation, particularly at the UVend of the spectrum, acts together with atmosphericoxygen to cause embrittlement and yellowing. Thesechanges occur mainly in the butadiene elastomer.

Styrosun� resins are resistant to sunlight andmaintain significant physical properties afterweathering. The weather-resistant properties ofStyrosun� resins are achieved by combiningproprietary UV stabilization technology with aninherently UV stable impact modifier.6

The key advantage of Styrosun� resin is theretention of physical properties after outdoorweathering. Applications using Styrosun� resinsmaintain functional product life and toughness afterUV exposure.6

Molded plaques of Styrosun� and typicalcompetitive outdoor polymers were exposed at fourdifferent locations in the United States and colorretention (as DE) was monitored over time. The color

Figure 4.54 Chemical structure of styrene acryloni-trile (SAN).

Table 4.11 Surface and Appearance Propertiesafter Arizona Outdoor Weathering of Dow Tyril�

1020 Transparent, UV-Stabilized SAN Copolymer21

Exposure Time (Days) 1095


Tensile Strength 101

Elongation 100

Surface and Appearance e

DYellowness Index 5.5

Haze Retained (%) 143.2

Luminous Transmittance Retained (%) 99.8

Figure 4.55 Yellowness indexafter Arizona outdoor weatheringof Dow Tyril� SAN copolymer.21


retention performance of Styrosun� HIPS, acrylo-nitrile-styrene-acrylate (ASA), UV-stabilized ABS(UV-ABS), UV-stabilized high-impact polystyrene(UV-HIPS), and filled polypropylene (PP) wascompared after 18 months at four different exposuresites in the United States. The results demonstratedthat Styrosun� and ASA had equivalent performance(DE range 4.9e6.5). UV-ABS and UV-HIPS werealso equivalent in performance (DE range18.5e26.1). Filled PP exhibited the smallest change

in color over this exposure period (DE range1.6e2.2). A DE value of 5 or less is generallyconsidered to be negligible unless directly comparedto an unexposed control.18

Molded plaques of Styrosun� and various othermaterials were exposed in Xenon Arc Weather-Ometers� (Atlas Material Testing Technology LLC)as per ASTM protocol G155 Cycle 2 (ASTM,American Society for Testing and Materials, is aninternational standards organization that develops and

Figure 4.56 Yellowness index afterAtlas UV-CON� accelerated weath-ering exposure of SAN copolymer.11

Table 4.12 Color Properties after Florida (45� South Facing) Outdoor Exposure for Pigmented GE PlasticsGeloy� ASA22

Color Country Green Siding Pebblestone Siding

Exposure Conditions

Exposure Time (Months) 0 6 12 18 24 0 6 12 18 24


CIELab Color Coordinates and Color Shift (D/2�)

L 66.2 65.6 65.6 66.1 66.3 62.5 62.3 62.2 62.6 62.4

a �6.8 �6.7 �6.7 �6.7 �6.8 1.4 1.4 1.3 1.4 1.3

b 7.8 7.7 8.3 8.3 8.3 11 10.9 11.3 11.4 11.2

DE 0 0.6 0.8 0.5 0.5 0 0.2 0.4 0.4 0.2

DL 0 �0.6 �0.6 �0.1 �0.1 0 �0.2 �0.3 0.1 �0.1

Da 0 0.1 0.1 0.1 0 0 0 �0.1 0 �0.1

Db 0 �0.1 0.5 0.5 0.5 0 �0.1 0.3 0.4 0.2

Note: See Chapter 3.2.1 for an explanation of color coordinates


publishes voluntary consensus technical standards).By calculation, 3000 h of accelerated weathering bythis protocol is theoretically equivalent to 1 year ofexposure in Florida or 0.8 years in Arizona. The colorretention of white Styrosun� after 3000 h of accel-erated weathering was identical to its color retentionafter 18 months of Florida outdoor weathering. In thisaccelerated exposure test, neither ASA nor UV-ABS

exhibited the same degree of color change seen afterFlorida exposure. However, UV-ABS was again lessresistant to color change than Styrosun�. Filled PPexhibited the smallest change in color over thisexposure period. Examination of the acceleratedweathering DE graph also illustrates the significantamount of scatter in the data.18

The samples were also tested for retained impactstrengths. There are three impact results reported bya Dynatup� (Instron Corporation) impact test instru-ment. The “energy at maximum load” is the energy atthe moment of impact, the “total energy” is the energyrequired to break the test plaque, and the “maximumload” is the weight required to break the test plaque.When these absolute numbers were compared, inall cases, Styrosun� was stronger and tougher thanfilled PP, but not as strong as UV-ABS. Whenthe percentage retention values were compared,Styrosun� was found to retain its properties signifi-cantly better than UV-ABS and similar to filled PP.18

Addition of UV stabilizers overcomes the yel-lowing and brittleness associated with prolongedexposure of unmodified HIPS to sunlight.18 Combi-nations of UVAs and hindered amine light stabilizerscan provide improved performance.19

Data for HIPS plastics are found in Tables4.8e4.10 and Figs 4.44e4.53.

4.3.3 Syndiotactic Polystyrene

Syndiotactic polystyrene (SPS) is a semi-crystalline polymer synthesized from styrenemonomer using a single-site catalyst such as

Table 4.13 Yellowness Index after Outdoor Weathering in Ludwigshafen, Germany, for BASF Luran� S 776 SHigh-Impact, Moderate-Flow ASA Polymer3

ExposureTime (Days)

15 30 45 60


NotchedImpactStrength

98.6 (notched sideexposed to light)




ImpactStrength

100 (no break;struck onunexposed side,thus subjectingexposed side todynamic loading)




Table 4.14 Color Shift and Gloss Retention after SAEJ1960AcceleratedWeathering: 2500 kJ ofGeloyXTWResin Colors26

ColorColor ChangeDE (Units)

Gloss RetentionRetained (%)

Black 0.1 92

RoyalBlue

1.8 72

SilverGray

1.7 93

Red 1.2 85

BrightWhite

0.1 85

Yellow 1.8 66

Ivory 0.75 90

Green 0.5 94

IvoryPaint

1.0 83

GreenPaint

1.8 85


Figure 4.57 Yellowness indexafter outdoor sunshine exposurefor BASF Luran� S 797 and Luran�

S 776 ASA polymer.23

Figure 4.58 Color change, DE,after outdoor weathering inOkinawa, Japan, for MitsubishiRayon� ASA polymer.20

Figure 4.59 Impact strengthretained after outdoor weatheringin Okinawa, Japan, for MitsubishiRayon� ASA polymer.11


Figure 4.60 Elongation at breakretained after outdoor weatheringin Okinawa, Japan, for MitsubishiRayon� ASA polymer.11

Figure 4.61 Gloss retained afteroutdoor weathering in Okinawa,Japan, for Mitsubishi Rayon� ASApolymer.11

Figure 4.62 Impact strengthretained at 63 �C after sunshineWeather-Ometer� exposure forMitsubishi Rayon� T110 and T120ASA polymer.11


Figure 4.63 Impact strengthretained at 63 �C after sunshineWeather-Ometer� exposure forMitsubishi Rayon� ASA polymer.11

Figure 4.64 Elongation at breakretained at 63 �C after sunshineWeather-Ometer� exposure forMitsubishi Rayon� ASA polymer.11

Figure 4.65 Gloss retained at63 �C after s1unshine Weather-Ometer� exposure for MitsubishiRayon� T115 and T110 ASApolymer.13


Figure 4.66 Gloss retained at63 �C after sunshine Weather-Ometer� exposure for MitsubishiRayon� ASA polymer.11

Figure 4.67 Impact strengthafter Weather-Ometer� expo-sure for BASF Luran� SASA polymer at different testtemperatures.3

Figure 4.68 Impact strengthafter Xenotest 1200 exposurefor BASF Luran� S 797 andLuran� S 776 ASA polymer.23


Figure 4.69 Yellowness index ofABS, Luran� S, and blends afterexposure to sunshine.8

Figure 4.70 Toughness in theISO 6603-2 penetration testafter outdoor weathering inGermany; penetration energyon 2-mm-thick disks.24

Figure 4.71 Yellowing of ABS,Luran� S and blends on outdoorweathering (white pigmentation).24


Figure 4.72 Luran S ASAretains its impact propertiesvery well when exposed tooutdoor weathering conditions,as shown in this graph, throughan accelerated weathering test,in comparison to both UV-stabi-lized and nonstabilized ABS.25

Figure 4.73 Luran S ASA offersexcellent impact properties overa wide range of temperatureseven after 4 years of weatheringin Arizona field weatheringstudy.25

Figure 4.74 Luran S ASAretains color better than coloredPVC (Polyvinyl Chloride) inOhio field weathering study.Measurements with 45�/0�spectrophotometer.25


Figure 4.75 Field color retentionstudy of light blue Luran S ASA in -Arizona (dry, sunny), Florida(wet, sunny) and Ohio (industrial).Measurements with 45�/0�spectrophotometer.25

Figure 4.76 Dark blue Luran SASA weathered in Germany(similar environment to NorthWest Pacific) shows excellentcolor-fade resistance even after4 years of continuous outdoorexposure. This particular darkblue initially shifts into the bluedirection and stays on theblue side over a 4-year expo-sure period and shows virtuallyno yellowing. Color measure-ments with CIELAB d/8spectrophotometer.25

Figure 4.77 Dark brown LuranS ASA weathered in Germany(similar environment to North-west Pacific) shows excellentcolor-fade resistance even after4 years of continuous outdoorexposure. This particular darkbrown shows very little colori-metric shift in either measure-ment direction, thereby visuallyretaining its original look. Colormeasurements with CIELABd/8 spectrophotometer.25


metallocene. Because of its semicrystalline nature,SPS products exhibit performance attributes that aresignificantly different from those of amorphousstyrenic materials. See Section 1.7.3 for an expla-nation of the structural differences of syndiotactic vs.atactic polymer structures.

Dow Plastics had made Questra SPS, but has sincediscontinued these products in 2004. Xarec� SPS,which is made by Idemitsu and is distributed byPolymer Technology and Services, LLC (PTS), isa successor product to Questra. Dow Chemical hasredirected all new customer inquiries to Idemitsu

and also transferred all U.L. ratings (UnderwritersLaboratories, an Independent, not-for-profit productsafety testing and certification organization) fromQuestra to the Idemitsu Xarec� file. Idemitsu Kosaninvented SPS resin back in 1985. Several companiesincluding RTP, compound plastic formulations basedon SPS.

4.4 SAN Copolymer

Styrene and acrylonitrile monomers can be copo-lymerized to form a random, amorphous copolymer

Figure 4.78 Gloss shift afterASTM G26 accelerated weath-ering of traditional ASA vs.Geloy XTW resin (black).26

Figure 4.79 Color shift afterASTM G26 accelerated weath-ering of traditional ASA vs.Geloy XTW resin (black).26


that has good weatherability, stress crack resistance,and barrier properties. The copolymer is calledstyrene acrylonitrile or SAN. The SAN copolymergenerally contains 70e80% styrene and 20e30%acrylonitrile. It is a simple random copolymer. Thismonomer combination provides higher strength,rigidity, and chemical resistance than polystyrene,but it is not quite as clear as crystal polystyrene andits appearance tends to discolor more quickly. Thegeneral structure is shown in Fig. 4.54. Its CASnumber is 9003-54-7.

Manufacturers and trade names: BASF Luran�,Dow Chemical TYRIL Resins.Applications and uses: Household: mixing bowls,

electric mixers, refrigerator inserts, tableware,vacuum flask casings, food storage containers,toiletries, cosmetics packaging, writing implements,and industrial batteries.Weathering Properties: Photodegradation chem-

istry is complex and can lead to production of smallmolecules including hydrogen, water, carbon di-oxide, ketone, hydroperoxides, benzene, acetophenone,

Figure 4.80 Gloss shift afterASTM G26 accelerated weath-ering of current ASA vs. GeloyXTW resin (white).26

Figure 4.81 Yellow shift afterASTM G26 accelerated weath-ering of current ASA vs. GeloyXTW resin (white).26


benzaldehyde, formic acid, acetic acid, benzoic acid.The polymer may form conjugated double bonds,unsaturations, radicals, chain scissions, cross-links,quinomethane structures. This leads to yellowing, lossof gloss, loss of mechanical performance.

Stabilization1:UVA: such as 2,4-dihydroxybenzophenone.HAS: such as Chimassorb� 119 from Ciba/BASFData for SAN copolymer plastics are found in

Table 4.11 and Figs 4.55 and 4.56.

4.5 Acrylonitrile-Styrene-Acrylate

ASA is the acronym for acrylate rubber modifiedSAN copolymer. ASA is a terpolymer that can beproduced by either a reaction process of all threemonomers or by a graft process. ASA is usually madeby introducing a grafted acrylic ester elastomerduring the copolymerization of styrene and acrylo-nitrile, known as SAN. SAN is described in the nextsection of this chapter. The finely divided elastomerpowder is uniformly distributed and grafted to theSAN molecular chains. The outstanding weather-ability of ASA is due to the acrylic ester elastomer.ASA polymers are amorphous plastics, which havemechanical properties similar to those of the ABSresins described in Section 4.2. However, the ASAproperties are far less affected by outdoor weathering.

ASA resins are available in natural, off white, anda broad range of standard and custom-matchedcolors. ASA resins can be compounded with otherpolymers to make alloys and compounds that benefitfrom ASA’s weather resistance. ASA is used in manyproducts including, lawn and garden equipment,sporting goods, automotive exterior parts, safetyhelmets, and building materials.

Weathering: ASA is inherently stable to UV andweathering degradation processes which can beimproved even further with UVAs and antioxidants.

Stabilization: UV stabilizers such as 2-(2H-ben-zotriazol-2-yl)-p-cresol are used. Phenolic antioxi-dants and carbon black are often used.1

Data for ASA plastics are found in Tables4.12e4.14 and Figs 4.57e4.81.

References

1. Wypych George. Handbook of UV degradationand stabilization. ChemTec Publishing; 2011.

2. Rovel weatherable polymers. Supplier technicalreport (301-621-285). Dow Chemical Company;1985.

3. Luran S. Acrylonitrile styrene acrylate productline, properties, processing. Supplier designguide (B 566 e/10.83). BASFAktiengesellschaft;1983.

4. Polystyrol product line, properties, processing.Supplier design guide (B 564 e/2.93). BASFAktiengesellschaft; 1993.

5. Cycolac ABS resin design guide. Supplier designguide (CYC-350 (5/90) RTB). General ElectricPlastics; 1990.

6. Styrosun, Nova Chemicals. 2005.7. Perez JM, Vilas JL, Laza JM, Arnaiz S,

Mijangos F, Bilbao E, et al. Effect of reproc-essing and accelerated weathering on ABSproperties. J Polym Environ 2009;18:71e8.

8. Weather: Color and fading properties. UMGABSLtd.; 2005.

9. Engineering design guide to rigid geon custominjection molding vinyl compounds. Supplierdesign guide (CIM-020). BF Goodrich GeonVinyl Division; 1989.

10. Duracap vinyl capstock compounds, suppliermarketing literature (DC-001). BFGoodrichGeon Vinyl Division; 1988.

11. Supplier technical data provided for the effect ofUV light and weather. 1st ed. 1994.

12. Weatherability of Cycolac brand ABS. Tech-nical Publication P-405 supplier technicalreport (8203-5M). General Electric Company;1982.

13. Shinko-Lac ASA T weatherable and heat resis-tant ASA resin, Supplier design guide, Mitsu-bishi Rayon Company.

14. Introducing superior UV stability with goodlooks that last in business machine housings.Supplier marketing literature (7110). MonsantoChemical Company; 1990.

15. Cloud P, Theberge J. Glass-reinforced ther-moplastics, thermal and environmental resis-tance of glass reinforced thermoplastics.Supplier technical report. LNP Corporation;1982.

16. Osswald Tim A, Baur Erwin, Brinkmann Sigrid,Oberbach Karl, Schmachtenberg Ernst. Inter-national plastics handbookdThe resource forplastics engineers. 4th ed. Hanser Publishers;2006.


17. Styron 6000 ignition resistant polystyrene resins.Supplier marketing literature (301-01673-192RSMG). Dow Chemical Company; 1992.

18. Color and impact property retention of Styrosun�

polymers after accelerated weathering. TechnicalBulletin. SA: INEOS NOVA International; 2009.

19. High impact polystyrenedHIPS UV Stabilised.Azom, Inc.; 2005.

20. UV light stabilization of HIPS. S.A.: Special-Chem; 2005.

21. Tyril SAN engineering and fabrication guide-lines. Supplier design guide (301-665-1085).Dow Chemical Company; 1985.

22. Cycolac/Geloy products and markets. GE Plas-tics; 2005.

23. Luran S. Acrylonitrile styrene acrylate productline, properties, processing. Supplier designguide (B 566 e/11.90). BASF Aktiengesellschaft;1990.

24. The properties of Luran� S. KS/KC, E100.BASF Aktiengesellschaft; 2007.

25. Luran� S. ASA extrusion grades, performancecomparisons and applications. LUR 5/01/500.BASF Corporation; 2001.

26 Geloy* XTW ASA resin. PLA-700-REV5-1006.General Electric Company; 2006.


5 Polyesters

5.1 Polyesters

Polyesters are formed by a condensation reactionthat is very similar to the reaction used to makepolyamide or nylons. A diacid and dialcohol arereacted to form the polyester with the eliminationof water as shown in Fig. 5.1. The monomers ofeach polyester are described in each plasticsection.

While the actual commercial route to making thepolyesters may be more involved, the end result isthe same polymeric structure. The diacid is usuallyaromatic. Polyester resins can be formulated to bebrittle and hard, tough and resilient or soft andflexible. In combination with reinforcements suchas glass fibers, they offer outstanding strength,a high strength-to-weight ratio, chemical resistanceand other excellent mechanical properties. Thethree dominant materials in this plastics family arepolycarbonate (PC), polyethylene terephthalate(PET) and polybutylene terephthalate (PBT).Thermoplastic polyesters are similar in properties toNylon 6 and Nylon 66, but have lower waterabsorption and higher dimensional stability than thenylons.

Weathering: UV radiation absorbed by polyestersleads to scission (breaks in the polymer chains)reactions centered on the ester linkages as shown inFig. 5.2. This leads to formation of small moleculessuch as carbon monoxide and carbon dioxide andpolymer chains with hydroxyl, carboxyl and alde-hyde end groups. Reaction of the radicals producedby photolysis with oxygen can produce chain scis-sion and molecular weight reduction and carbonylformation. Recombination of transient radicals canlead to cross-linking of the polymer. When water ispresent, hydrolysis occurs.

Stabilization1: Polyesters are stabilized with:

� UVA: such as 2-hydroxy-4-octyloxybenzophe-none and 2-(2H-benzotriazol-2-yl)-p-cresol

� HALS: such as 1,3,5-triazine-2,4,6-triamine,N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-(Chimassorb� 119 from Ciba/BASF)]

� Screener: carbon black, zinc oxide

� Acid scavenger: hydrotalcite


� Phosphite: such as bis-(2,4-di-t-butylphenol) pen-taerythritol diphosphite

� Optical brighteners: such as 2,20-(2,5-thiophene-diyl)bis(5-tert-butylbenzoxazole)

5.2 Liquid Crystalline Polymers

Liquid crystalline polymers (LCPs) are a rela-tively unique class of partially crystalline aromaticpolyesters based on 4-hydroxybenzoic acid andrelated monomers shown in Fig. 5.3. LCPs arecapable of forming regions of highly ordered struc-ture while in the liquid phase. However, the degree oforder is somewhat less than that of a regular solidcrystal. Typically, LCPs have outstanding mechan-ical properties at high temperatures, excellentchemical resistance, inherent flame retardancy andgood weatherability. Liquid crystal polymers comein a variety of forms from sinterable high tempera-ture to injection-moldable compounds.

Figure 5.1 Chemical structureof polyester.




LCPs are exceptionally inert. They resist stresscracking in the presence ofmost chemicals at elevatedtemperatures, including aromatic or halogenatedhydrocarbons, strong acids, bases, ketones and otheraggressive industrial substances. Hydrolytic stabilityin boiling water is excellent. Environments thatdeteriorate these polymers are high-temperaturesteam, concentrated sulfuric acid and boiling causticmaterials.As an example, the structure of Ticona Vectra�

A950 LCP is shown in Fig. 5.4.Weathering Properties: LCP resins exhibit

excellent mechanical property retention after expo-sure to weathering.2

After 2000 h of artificial weathering, moldingsmade from Vectra� retained more than 90% of theirinitial mechanical property values. After one year ofoutdoor weathering, a slight white deposit wasdetected. The white deposit is the degraded materialthat appears on the surface (chalking) and results ina reduction in gloss, color change and deteriorationof mechanical properties.3

Manufacturers and Trade names: EastmanThermx�, DuPont Engineering Polymers Zenite�,Ticona Vectran� and Vectra�, Solvay AdvancedPolymers Xydar�, Sumitomo Sumikasuper�, ToraySiveras�.Applications and uses: Data for LCP plastics are

found in Tables 5.1 and 5.2.

5.3 Polybutylene Terephthalate

PBT is semicrystalline, white or off-white poly-ester similar in both composition and properties to

PET. It has somewhat lower strength and stiffnessthan PET, and is a little softer but has higher impactstrength and similar chemical resistance. As it crys-tallizes more rapidly than PET, it tends to bepreferred for industrial scale molding. Its structure isshown in Fig. 5.5.PBT performance properties include:

� High mechanical properties

� High thermal properties

� Good electrical properties

� Dimensional stability

� Excellent chemical resistance

� Flame retardancy

Weathering Properties: PBT products sufferfrom cracking, yellowing, loss of gloss and deterio-ration of tensile impact properties when exposed toUV light.5

Moldings made from Ultradur� and exposed tothree years of open air weathering in central Europetend to discolor very slightly and their surfacescarcely changes. Mechanical properties such asrigidity, tensile strength and tear strength are slightlyaffected. After a weathering test for 3600 h in theXenotest� 1200, the tensile strength retained is 90%of the initial value. However, elongation at break ismore adversely affected. Based on experience,3600 h in the Xenotest� 1200 equipment corre-sponds to about 5e6 years of weathering in open air.Parts for outdoor use should be manufacturedfrom black-colored material in order to prevent

Figure 5.2 Photolysis of polyes-ters produces various radicalspecies.


impairment of strength due to surface attack. Fiber-reinforced PBT grades such as Ultradur� B 4040 G4/G6/G10 with outstanding surface quality and highresistance to UV radiation are suitable for parts thatare subject to particularly extreme exposure. Thesegrades have outstanding surface quality and exhibithigh resistance to UV radiation.6

Results taken after three years of outdoor exposureindicate that there is no fundamental change inphysical properties. Predictably, black Celanex�

Figure 5.3 Chemical structures ofmonomers used to make liquidcrystalline polymer polyesters.

Figure 5.4 Chemical structure of Ticona Vectra�

A950 LCP.

5: POLYESTERS 109

3300 polyester resin exhibits better property reten-tion than natural resins and should therefore beconsidered where long-term outdoor exposure isrequired.7

Stabilization: Stabilizers for PBT are those dis-cussed in the introduction of this chapter. However,Ciba Tinuvin� 234 and Tinuvin� 1577 can offerPBT products of high-quality UV protection.5

Manufacturers and trade names: BASFUltradur�, DuPont Crastin�, PolyOne Burgadur�,SABIC Innovative Plastics Enduran, TiconaCelanex�.Applications and uses: packaging, automotive,

electrical and consumer markets.Data for PBT plastics are found in Tables 5.3e5.6

and Figs 5.6e5.29.These DuPont Engineering-Plastics Crastin� PBT

products are presented in the following table andfigures:

1. Crastin� S600F10 NC010 is an unreinforced,lubricated, medium high viscosity PBT resinfor injection molding.

2. Crastin� SO655 NC010 is basic, 30% glassbead filled grade PBT resin.

Table 5.1 Results of Artificial Weathering for 2000 h of Ticona Vectra� A130 and Vectra� B950 LCPs4

Properties Retained (%) Vectra A950 Vectra A130 Test Method

Tensile Strength 95 95 ASTM D638

Tensile Modulus 90 98 ASTM D638

Flexural Strength 95 95 ASTM D790

Flexural Modulus 95 95 ASTM D790

HDT at 1.82 MPa 90 92 ASTM D648

Notched Izod 90 95 ASTM D256

Note: (1) ASTM D2565dxenon arc lamp, air temperature 125 �C, water spray for 18 min every 202 min.

Table 5.2 Mechanical Properties Retained after Xenon Arc Accelerated Weathering for Ticona Vectra� A950,Vectra� A130, Vectra� B950, and Vectra� A540 LCPs3

LCP Grade Vectra® A950 Vectra® A130 Vectra® B950 Vectra® A540

Filler 30% Glass Fiber 40% Mineral


Tensile Modulus 90 100 93 95

Flexural Modulus 100 100 95 100

Tensile Strength 97 97 100 100

Flexural Strength 100 100 100 100

Notched Izod ImpactStrength

91 100 100 100

Heat DeflectionTemperature

92 94 99 93

Note: (1) Test method: ASTM D2526, water spray for 18 min every 202 min. (2) Temperature 125 �C. (3) Exposure time:83.3 days.

Figure 5.5 Chemical structure of polybutylene tere-phthalate (PBT) polyester.


Table 5.3 Ticona Celanex� PBT PolyestersdColor Difference and Gloss Change after 2 Years of Exposure inSouth Florida8

60% Gloss Readings (%)

Celanex®

Grades Condition DLa Daa Dba DEa Initial Final Retention

1462Z BK225 As is �3.62 0.20 0.87 3.73 24.0 5.0 20.8

Washed 0.62 0.04 0.49 0.80 24.0 10.3 42.9

6500 BK225 As is �5.05 0.25 0.61 5.09 88.0 14.4 16.4

Washed 0.43 0.02 0.02 0.43 88.0 36.8 41.8

Washed andpolished

�3.26 0.01 �0.39 3.29 88.0 25.3 28.8

6407 ED3807 As is �1.35 �0.15 0.12 1.36 44.5 3.2 7.2

Washed 0.50 0.04 0.69 0.85 44.5 17.4 39.1

2002-2 ED3807 As is �6.58 0.53 1.34 6.74 92.3 29.5 32.0

Washed �0.70 �0.01 0.39 0.80 92.3 67.7 73.3

Washed andpolished

�0.39 �0.09 �0.54 0.67 92.3 71.8 77.8

Note: (1) Test method: SAE J1976.aD means the change in the value (i.e. the exposed value minus the initial value).

Table 5.4 Changes in Color and Gloss of Ticona Celanex� PBT Polyester Prototype Parts after 2500 kJ/m2

Exposure to Xenon Arc8

Celanex®

GradesPart

Description Surface Condition DL* Da* Db* DE*

6500 BK225 F-car wiper airfoil Textured As is �1.96 0.27 1.61 2.55

Washed 1.70 �0.01 0.27 1.72

Washed andpolished

0.16 0.02 0.32 0.36

2002-2 ED3807 F-car wiper cover Textured As is 0.87 �0.73 2.50 2.82

Washed 3.77 �0.06 0.16 3.77

6407 ED3807 Luggage rack rail Smooth As is 0.15 0.19 0.77 0.81

Washed �0.81 �0.49 �0.01 0.94

Note: (1) Test method: SAE J1960.

Table 5.5 Mechanical Property Retention of Ticona Celanex� PBT Polyesters after 2500 kJ/m2

Exposure to Xenon Arc8

Properties Retained (%) Units Celanex® 6500 BK225 Celanex® 6407 ED3807

Tensile Strength at Break % 97 97

Elongation at Break % 94 93

Notched Izod % 102 89

Flexural Strength % 94 92

Flexural Modulus % 101 100

Note: (1) Test method: SAE J1960.

5: POLYESTERS 111

3. Crastin� SK605 BK851 is 50% glass fiberreinforced, lubricated, black PBT resin forinjection molding.

4. Crastin� SK603 NC010 is 20% glass fiberreinforced, lubricated PBT resin for injectionmolding.


6. Crastin� SK645FR NC010 is a flame retar-dant, 30% glass reinforced natural PBTmolding resin. It is recognized as UL94V-0at 0.75 mm.


8. Crastin� HTI619 NC010 is a 50% glass/mineral reinforced, high-tracking PBT resin.

9. Crastin� HTI681 NC010 is a low-warpageglass bead/mineral-reinforced, high-trackingPBT resin.

10. Crastin� T805 NC010 is a 30% glass fiber-reinforced, high-impact PBT resin for injec-tion molding.

11. Crastin� LW9130 NC010 is a low-warpage,30% glass-reinforced PBT resin.

5.4 Polycarbonate

Theoretically, PC is formed from the reaction ofbis-phenol A and carbonic acid. The structures ofthese two monomers are given in Fig. 5.30.

Table 5.6 Retention of Properties after Natural Weathering in Central Germany for Three DuPont Crastin� PBTGrades9

Crastin®

GradeTestMethod

WeatheringTime

(Years)

TensileStrength(%) DIN53455

TensileModulus(%) DIN53457

FlexuralStrength(%) DIN53452

CharpyImpactStrength

Unnotched(%) ISO 179

CharpyImpactStrength

Unnotched(%) ISO 179

S600F10NC010

0 100 100 100 NB 100

1/2 92 102 99 NB 33

1 96 107 101 NB 40

2 91 108 99 NB 41

3 91 89 101 92.9 kJ/m2 45

4 93 98 98 89.5 kJ/m2 29

SK605NC010

0 100 100 100 100 100

1/2 87 93 96 90 100

1 92 87 91 82 99

2 75 95 79 64 89

3 81 97 81 68 83

4 76 83 79 52 81

SO655NC010

0 100 100 100 100 (100)a 100

1/2 92 86 9/8 47 (61) 60

1 90 92 100 65 (69) 58

2 83 98 93 61 (72) 60

3 85 83 91 55 (60) 57

4 85 90 87 43 (68) 52

Note: (1) Change of properties vs. unexposed products.aIn this case the values are based on the value at the beginning of the storage. The figures in parenthesis represent the impactstrength changeofnonexposed samples anddependon the storage time in the test laboratory vs. the initial start of the test program.


Figure 5.6 Notched Izod impactstrength after Florida and Arizonaoutdoor weathering for TiconaCelanex� PBT.10

Figure 5.7 Tensile strength afterFlorida and Arizona outdoorweathering for Ticona Celanex�

PBT.10

Figure 5.8 Flexural strength atbreak after Hiratsuka, Japan,outdoor exposure of PBTpolyester.11

5: POLYESTERS 113

Figure 5.9 Flexural modulus afterHiratsuka, Japan, outdoor expo-sure of PBT polyester.11

Figure 5.10 Notched Izod impactstrength after Hiratsuka, Japan,outdoor exposure of PBTpolyester.11

Figure 5.11 Weight change afterHiratsuka, Japan, outdoor expo-sure of PBT polyester.11


Figure 5.12 Tensile strengthretained after Weather-Ometer�

exposure of Ticona Celanex�

PBT.10

Figure 5.13 Change in yellow-ness index, YI, after light exposureof PBT injection-molded plaques.5

Note: Xenon arc weathering, ISO4892-2, cycle 102/18; 1 mmplaques; base stabilization: 0.10%Irganox� 1010 and 0.40%Irgafos� 168 (Irganox� B 561).

Figure 5.14 Stress at break ofBASF Ultradur� PBT after weath-ering with xenon arc per ISO4892-2 ref. A.12

5: POLYESTERS 115

Figure 5.15 Stress at break ofBASF Ultradur� high speed PBTafter weathering per xenon arcISO 4892-2 ref. A.12

Figure 5.16 Charpy impactstrengthofUltradur� PBTafterdiffe-rent weathering with xenon arc perISO 4892-2 ref. A.12

Figure 5.17 Charpy impactstrength of Ultradur� high speedPBT after weathering with xenonarc per ISO 4892-2 ref. A.12


Figure 5.18 Tensile strength vs.outdoor exposure at Kitakyusyucity Japan of Mitsubishi Engi-neering-Plastics Novaduran PBT.13

Figure 5.19 Elongation at breakvs. outdoor exposure at Kitakyusyucity Japan of Mitsubishi Engi-neering-Plastics Novaduran PBT.13

Figure 5.20 Elongation at breakvs. sunshine carbon arc exposureat 63 �C with rain 12/60 min of Mit-subishi Engineering-Plastics Nova-duran Black PBT.13

5: POLYESTERS 117

Figure 5.21 Tensile strength vs.sunshine carbon arc exposure at63 �C with rain 12/60 min of Mitsu-bishi Engineering-Plastics Nova-duran PBT.13

Figure 5.22 Tensile strength vs.sunshine carbon arc exposure at63 �Cwith no rain ofMitsubishi Engi-neering-Plastics Novaduran PBT.13

Figure 5.23 Tensile fracture strainvs. sunshine carbon arc exposure at63 �Cwith no rain of Mitsubishi Engi-neering-Plastics Novaduran PBT.13


Figure 5.24 Weather-Ometer�

exposure effects on tensile strength,glass reinforced grades of TiconaCelanex� PBT polyester.8

Figure 5.25 Tensile strength vs.outdoor exposure in Florida and Ari-zona, glass reinforced grades ofTicona Celanex� PBT polyester.8

Figure 5.26 Izod impact vs.outdoor exposure in Florida andAri-zona, glass reinforced grades ofTicona Celanex� PBT polyester.8

5: POLYESTERS 119

Figure 5.27 Effect of weatheringon flexural strength of someDuPontCrastin� PBT grades.9

Figure 5.28 Impact resistance(DIN53452) vs. weathering time ofsome DuPont Crastin� PBTgrades.9

Figure 5.29 Impact strength vs.weathering time of DuPontCrastin� S600F10 NC010.9


Commercially, different routes are used (differentmonomers), but the PC polymer of the structureshown in Fig. 5.31 is the result.

PC performance properties include:

� Very high impact resistance and is virtually un-breakable and remains tough at low temperatures

� “Clear as glass” clarity

� High heat resistance

� Dimensional stability

� Resistant to ultraviolet light, allowing exterior use

� Flame retardant properties

Weathering Properties: PC is used in buildingapplications, mainly as glazing material. “Whenirradiated with short wavelength UV-B or UV-Cradiation, PCs undergo reactions referred to as

Figure 5.30 Chemical structures of monomers usedto make polycarbonate polyester.

Figure 5.31 Chemical structure of polycarbonate(PC) polyester.

Figure 5.32 The photo-Fries rearrangement in polycarbonate.

5: POLYESTERS 121

Table 5.7 Izod Impact and Surface and Appearance Properties after Arizona Outdoor Exposure of Dow Calibre�

300 6 MFR with and without UV Stabilizer15

Features Without UV Stabilizer With UV Stabilizer

Time 0 6 Months 1 Year 2 Years 0 6 Months 1 Year 2 Years

Mechanical Properties

Izod Impact (ft-lb/in.) 17.6 17.9 1.2 0.6 18.2 17.9 17.7 18.5


Transmittance (%) 89.4 85.8 84.7 82.3 89.6 88.4 88.5 87.3

Haze (%) 1.7 8.2 12.7 19.8 1.6 6.8 9.0 14.8

Yellowness IndexIncrease

0 þ12.3 þ15.7 þ20.0 0 þ2.3 þ3.3 þ6.1

Note: (1) Exposure conditions Arizona, 45� angle facing south. (2) Exposure time 2 years.

Table 5.8 Mechanical Properties Retained after California and Pennsylvania Outdoor Exposure of LNP Engi-neering Plastics PC16




Tensile Strength 90 90.4 89 87 88 86 89 87

Notched Izod Impact Strength 94 83.3 94 83.3

Unnotched Izod Impact Strength 83 72.3 80 73.8

Note: (1) ASTM 1435. (2) Composition: 1% carbon black, 30% glass fiber.

Table 5.9 Mechanical Properties and Surface and Appearance Properties after Arizona Accelerated OutdoorWeathering and Kentucky Outdoor Weathering for GE Lexan� S-100 and Lexan� 100 PC Sheet17

Material Characteristics

Sample Thickness (mm) 3.28 2.36 3.28 2.36 3.28 2.36

Exposure Conditions

Exposure Location Arizona Florence, Kentucky Arizona

Exposure Apparatus EMMAqua Carbon arcWeather-Ometer�

Exposure Note 45� angle south

Exposure Time (Days) 365 365 730 730 125 125


Tensile Strength 101 98

Notched Izod Impact Strength 84.2 64.7

Charpy Notched Impact Strength 10.9 55.7


DYellowness Index 17.29 20.91 10.46 9.0 25.43 25.0

Luminous Transmittance Retained (%) 90.6 88.4


Table 5.10 Mechanical Properties Retained after X-W Accelerated Weathering for GE Lexan� 303 PC18

Exposure Time (Days) 41.7 83.3 166.7 333.3



42 9 9 9

Tensile Impact Strength 30 38 29

Heat DeflectionTemperature

100.8 101.5 100 98.5

Table 5.11 Influence of Pigment Addition to in Mitsubishi Engineering-Plastics Iupilon�/Novarex PC in OutdoorExposure test19

Type of PigmentAdditive Amount (%)

AdditiveAmount

(%) pH

UntreatedOutdoor Exposure

1 Year

Thickness(mm)

MolecularWeight(3104)

MolecularWeight(3104) DE

Blue Pigment 0.2 9.4 2.8 2.1 5.6 50

Red Oxide 0.2 7.6 2.8 2.1 4.9 50

Shanin Green 0.2 6.5 2.8 2.1 4.3 50

Cadmium Yellow M3600 0.2 7.3 2.8 2.1 2.2 50

Cadmium Yellow M3200 0.2 7.2 2.8 2.1 1.8 50

Cadmium Red L6600 0.2 8.2 2.8 2.2 2.6 50

Cadmium Red M8300 0.2 8.2 2.8 2.1 2.7 50

Cadmium Red 05700 0.2 8.1 2.8 2.6 2.9 50

0.2 Shanin Blue LBGT 8.0 2.8 2.3 1.0 50

Carbon Blacks

Nippiru#100 (Nittetsu) 0.5 4.7 2.8 2.4 3.0 50

FB44 (Mitsubishi Carbon) 0.5 7.7 2.8 2.3 3.8 50

#50 (Mitsubishi Carbon) 0.5 6.0 2.8 2.3 4.5 50

#600 (Mitsubishi Carbon) 0.5 7.0 2.8 2.5 5.6 50

For Rubber H(Mitsubishi Carbon)

0.5 7.7 2.8 2.5 2.5 50

Mark (Columbia) 0.5 3.0 2.8 2.4 9.0 50

#999 (Columbia) 0.5 2.8 2.3 7.0 50

Blank 0 3.9 2.8 1.8 8.2

Titanium White R820 0.7 2.8 13.6 200

Titanium White R101 0.7 2.8 14.4 200

Carbon Black(For Rubber H)

0.5 2.8 2.0 200

Carbon Black (#100) 0.5 2.8 2.6 4.4 200

Blank 0 2.8 2.0 11.0 200

5: POLYESTERS 123

Table 5.12 Influence of UV Stabilizer and Titanium Dioxide (TiO2) Content in Mitsubishi Engineering-Plastics Iupilon�/Novarex PC in Exposure TestPerformance Test19

Additives (%) Change in Melt Viscosity by Exposure test (3104) Generation Rate of Brittle Break by Falling Ball Test (%)

UV TiO2 0 Year 2 Years 3 Years 4 Years 5 Years 0 Year 1 Year 2 Years 3 Years 4 years

1 0 0 3.1 2.8 2.7 2.6 2.5 0 90 100 100 100

2 0.4 0 3.1 3.0 3.0 3.0 3.0 0 0 0 0 0

3 0 0.5 3.1 2.8 2.6 2.6 2.6 0 5 15 100 100

4 0.4 0.5 3.0 2.7 2.6 2.6 2.6 0 0 0 0 25

Note: (1) Sample thickness 2.5 mm, (2) The falling ball test drops the steel ball of 3.6 kg from the height of 3.85 m on a hemisphere body of 146 mm inside diameterand examines the breaking situation.

Figure 5.33 Transmittance throughtransparent GE plastics Lexan� PCafter Florida outdoor exposure asper ASTM G7.20

Figure 5.34 Yellowness index afterFlorida outdoor exposure as perASTM G7 for GE plastics Lexan�

PC.20

Figure 5.35 Haze after acceler-ated outdoor exposure of coatedand uncoated transparent GEplastics Lexan� PC.20

5: POLYESTERS 125

Figure 5.36 Yellowness indexafter accelerated outdoor expo-sure of coated and uncoated trans-parent GE plastics Lexan� PC.20

Figure 5.37 Yellowness indexafter xenon arc weathering for GEplastics Lexan� PC.20

Figure 5.38 Change in yellow-ness index, YI, after whirlygigaccelerated outdoor exposure ofGE plastics Lexan� PC.20


Figure 5.39 Yellowness indexafter Kentucky outdoor weatheringfor GE Lexan� S-100 sheet PC.17

Figure 5.40 Yellowness indexafter EMMAqua� accelerated ari-zona weathering for GE Lexan�

S-100 sheet PC.17

Figure 5.41 Haze (%) aftercarbon arc X-W weathering forGE Lexan� 153 PC.18

5: POLYESTERS 127

Figure 5.44 Degradation of tensileelongation by sunshine typeWeather-Ometer� (thickness200 mm) of Mitsubishi Engineering-Plastics Iupilon/Novarex PC.19

Figure 5.43 Change in discoloringto yellow of Mitsubishi Engi-neering-Plastics Iupilon/NovarexPC by outdoor exposure.19

Figure 5.42 Yellowness indexafter twin carbon arc weatheringfor GE Lexan� S-100 PC sheet.17


Figure 5.46 Degradation of APHA(color standard named for theAmerican Public Health Associa-tion and defined by ASTM D1209)color by sunshine type Weather-Ometer� (thickness 200 mm) ofMitsubishi Engineering-PlasticsIupilon�/Novarex PC.19

Figure 5.47 Degradation of hazeby sunshine type Weather-Ometer� (thickness 200 mm) ofMitsubishi Engineering-PlasticsIupilon�/Novarex PC.19

Figure 5.45 Degradation of meltviscosity by sunshine typeWeather-Ometer� (thickness200 mm) of Mitsubishi Engineering-Plastics Iupilon/Novarex PC.19

5: POLYESTERS 129

Figure 5.48 Light transmission vs.weathering exposure for EvonikCyrolon� PC.27 Comparing theweatherability of ACRYLITE Sheetvs. polycarbonate sheet, CYROIndustries, 2005. Note: Testmethod: ASTM D1003.

Figure 5.49 Color change, DE, ofpigmented GE plastics Cycoloy�

C1100 PC/ABS after acceleratedUV exposure as per SAE J1885(Atlas Ci65X-W) and DIN75202(Xenon 450).21

Figure 5.50 Color change, DE, ofpigmented GE plastics Cycoloy�

C1100 PC/ABS after acceleratedUV exposure as per SAE J1885(Atlas Ci65X-W) and DIN75202(Xenon 450).21


photo-Fries rearrangement.” This process is shown inFig. 5.32.

Humidity on its own does not affect PC much, butin conjunction with UV exposure it affects thebalance of the photo-Fries reaction vs. the photoox-idation reaction typical of polyesters. Products ofphotodegradation include hydroperoxides, free radi-cals, chain scissions, cross-links, hydroxyl groups,carbonyl groups, ethers and unsaturations. This leadsto embrittlement, surface erosion, loss of gloss, haze,discoloration and photobleaching.

PC sheet and injection molded parts may havea variety of coatings, including a range of hardcoatsthat enhance weathering, scratch and abrasionresistance.

Stabilization:UVA: such as 2-hydroxy-4-octyloxybenzophenone.Screener: such as zinc oxide.

Phenolic antioxidant: such as 2-(1,1-dimethy-lethyl)-6-[[3-(1,1-dimethylethyl)-2-hydroxy-5-meth-ylphenyl] methyl-4-methylphenyl acrylate.

Phosphite: such as tris (2,4-di-tert-butylphenyl)phosphite.

Optical brightener: such as 2,20-(2,5-thio-phenediyl)bis(5-tert-butylbenzoxazole).

Capped PC: surface layer made out of polymethylmethacrylate (PMMA) with10 wt% biphenyl-substituted triazine for glazing applications.

Tinuvin� 234, a benzotriazole UV absorber, iswell adapted to the UV stabilization of PC due toits low volatility, good initial color and compati-bility with PC. To achieve the highest possibleresistance to fading and weathering, Tinuvin�

1577, a UV absorber, may be used. This product isparticularly recommended for use in coextruded PCsheets.14

Manufacturers and trade names: Bayer Mate-rialScience Makrolon�, Dow Calibre�

Data for PC plastics are found in Tables 5.7e5.12and Figs 5.33e5.50.

5.4.1 Polycarbonate Blends

Weathering Properties: Cycoloy� resins exhibitexcellent UV stability. Slight color change and loss

Figure 5.51 Chemical structure of polyethyleneterephthalate (PET) polyester.

Table 5.13 Tensile Strength and Elongation Retained after Arizona Outdoor Weathering of DuPont Rynite� 545NC10, Rynite� 545 BK504, and Rynite� 935 BK50522

Material Grade Rynite 545 NC10 Rynite 545 8K504 Rynite 935 BK505

Features Natural Resin Black ColorBlack Color, Low-Warp

Grade

Material Composition

Glass FiberReinforcement

45% 45% 45% 45% 45% 45% 45% 45%

Mica/GlassFiberReinforcement

35% 35% 35% 35%

Exposure Conditions

Exposure Time(Days)

182 365 730 1095 182 365 730 1095 182 365 730 1095

Properties retained (%)

TensileStrength

98 88 87 82 94 97 94 90 100 100 100 97.5

Elongation 82 77 73 68 83 94 89 78 100 94 94 76

Note: (1) 45� south.

5: POLYESTERS 131

Table 5.14 Tensile Strength and Elongation Retained after Arizona Outdoor Weathering of DuPont Rynite� 530NC10 and Rynite� 530 BK50322

Material Grade Rynite 530 NC10 Rynite 530 BK503

Features Natural Resin Black Color


Glass Fiber Reinforcement 30% 30% 30% 30% 30% 30% 30% 30%

Exposure Conditions

Exposure Time (days) 182 365 733 1095 182 365 730 1095


Tensile Strength 100 98 90 87 98 100 98 98

Elongation 85 88 77 73 91 96 96 83


Table 5.15 Tensile Strength and Elongation Retained after Florida Outdoor Weathering of DuPont Rynite� 530NC10 and Rynite� 530 BK50322





Exposure Conditions





Table 5.16 Tensile Strength and Elongation Retained after Florida Outdoor Weathering of DuPont Rynite� 545NC10 and Rynite� 545 BK50422





Exposure Conditions






Table 5.17 Tensile Strength and Elongation Retained after Arizona EMMA and EMMAqua� Weathering ofDuPont Rynite� 530 NC10, Rynite� 530 BK503, Rynite� 545 NC10, and Rynite� 545 BK50422

Rynite MaterialGrade

530NC10

530BK503

545NC10

545BK504

530NC10

530BK503

545NC10

545BK504

FeaturesNaturalResin

BlackColor

NaturalResin

BlackColor

NaturalResin

BlackColor

NaturalResin

BlackColor

Material composition

Glass FiberReinforcement

30% 30% 45% 45% 30% 30% 45% 45%

Exposure Conditions

ExposureApparatus

EMMA EMMAqua�

Total Radiation(Langleys)

500,000 500,000


TensileStrength

100 100 92 93 100 100 92 93

Elongation 85 87 73 89 81 87 73 94

Exposure Note: (1) 150,000 Langleys is approximately equal to one year.

Table 5.18 Tensile Strength, Tensile Strain and Tear Resistance Polyethylene Terephthalate of Foil before,during and after Two Years of Exposure to Natural Weathering23

Exposuretime(Months)

TensileStrengthExtrusionDirection(NRa)

TensileStrength

PerpendicularDirection(NRa)

Elongationat BreakExtrusionDirection

(%)

Elongation atBreak

PerpendicularDirection (%)

TearResistanceExtrusionDirection(daN/cm)

TearResistance

PerpendicularDirection(daN/cm)

0 128 183 154 97 375 380

Continental Climate (Nikinci)

6 59.9 88.1 4.9 4.2 196 256

12 57.1 72.8 3.8 3.2 7 9

18 41.9 64.6 2.7 2.9 5 6

24 22.3 24.9 2.8 2.3 4 4


6 52.6 67.9 3.0 2.9 62 105

12 51.2 61.6 3.5 2.9 7 7

18 39.6 61.1 2.8 2.5 5 5

24 20.7 21.6 2.6 2.2 4 4

5: POLYESTERS 133

of mechanical properties can result after long-termexposure.21

Stabilization: Tinuvin� 234 protects PC blendsfrom the discoloration associated with exposure toUV light.14

5.5 Polyethylene Terephthalate

Polyethylene terephthalate (PET) polyester is themost common thermoplastic polyester and is often

called just “polyester”. This often causes confusionwith the other polyesters in this chapter. PET existsboth as an amorphous (transparent) and as a semi-crystalline (opaque and white) thermoplastic material.The semicrystalline PET has good strength, ductility,stiffness and hardness. The amorphous PET has betterductility but less stiffness and hardness. It absorbs verylittle water. Its structure is shown in Fig. 5.51.Weathering Properties: Rynite� 530 NC10 and

BK503 and Rynite� 545 NC10 and BK504 resins

Table 5.19 Color, Thickness and Flexibility at Low Temperature and Integral Light Transparency ofPolyethylene Terephthalate Foil before, during and after Two Years of Exposure to Natural Weathering23

ExposureTime(Months) Color Thickness (mm)

Flexibility atLow Temperature (L30�S)

Integral LightTransparency (%)

0 No color 0.14 No break 89





24 No color 0.14 Break 87





24 No color 0.14 Break 86

Table 5.20 Effect of Accelerated Weathering on the Retention of Original Physical Properties ofDuPont Rynite� PET Resins24

ExposureRynite® 530

NC010Rynite® 530

BK503Rynite® 545

NC010Rynite® 545

BK504

EMMAd500,000 Langleysa

TensileStrength

100 100 92 93

Elongation 85 87 73 89

EMMAqua�d500,000 Langleysa

TensileStrength

100 100 92 93

Elongation 81 87 73 94

Note: (1) EMMA¼ Equatorially mounted mirror assisted. (2) EMMAqua� ¼ EMMA assisted with water.a150,000 Langleys¼One year.


Figure 5.52 Tensile strength aftersunshine Weather-Ometer� expo-sure of PET.25

Figure 5.53 Elongation aftersunshine Weather-Ometer� expo-sure of PET.25

Figure 5.54 Changes of tensilestrength and elongation at breakof PET in longitudinal and perpen-dicular directions in continentalarea (Nikinci).23

5: POLYESTERS 135

Figure 5.55 Changes of tensilestrength and elongation at breakof PET in longitudinal and perpen-dicular directions in marine area(Kumbor).23

Figure 5.56 Changes of tearresistance of PET in longitudinaland perpendicular directions andintegral light transparency asa function of exposure time incontinental area (Nikinci).23

Figure 5.57 Changes of tear resis-tance in longitudinal and perpen-dicular directions and integral lighttransparency as a function of expo-sure time of PET in marine area(Kumbor).23


Figure 5.58 Changes of longitu-dinal tensile strength vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23

Figure 5.59 Changes of perpen-dicular tensile strength vs. expo-sure time of PET in continental(Nikinci) and marine areas(Kumbor).23

Figure 5.60 Changes of longitu-dinal tensile strain vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23

5: POLYESTERS 137

Figure 5.61 Changes of perpen-dicular tensile strain vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23

Figure 5.62 Changes of longitu-dinal tear resistance vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23

Figure 5.63 Changes of perpen-dicular tear resistance vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23


Figure 5.64 Changes of integrallight transparency vs. exposuretime of PET in continental (Nikinci)and marine areas (Kumbor).23

Figure 5.65 Percent retention oforiginal tensile strength after expo-sure in X-W Weather-Ometer ofDuPont Rynite� FR530 PETresins.24 Note: Rynite� FR530 is30% glass reinforced, flameretardant, modified polyethyleneterephthalate resin approved byUL as UL94V-0 at 0.35 mm.

Figure 5.66 (Figure 5.72) Percentretention of original tensilestrength after exposure in X-WWeather-Ometer DuPont Rynite�

PET resins.24 Note: Rynite�

FR530 is 30% glass reinforced,flame retardant, modifiedpolyethylene terephthalate resinapproved by UL as UL94V-0 at0.35 mm; Rynite� FR545 is 45%glass reinforced.

5: POLYESTERS 139

Figure 5.67 Retention of tensilestrength after 45� south outdoorFlorida weathering of DuPontRynite� PET resins.24

Figure 5.68 Retention of elonga-tion after 45� south outdoor Floridaweathering of DuPont Rynite�

PET resins.24

Figure 5.69 Retention of tensilestrength after 45� south outdoorArizona weathering of DuPontRynite� PET resins.24


have been exposed outdoors in Florida and Arizonafacing 45� south for three years. The data for thesesamples indicate that the resins have retained over72% of their initial tensile strength and over 50% oftheir initial elongation. The compositions containingcarbon black had higher property retention. Afterthree years, all the test samples were slightly“etched”.22

After 500,000 langleys of exposure in the Equa-torial Mount with Mirrors (EMMA) and EMMAwithwater spray (EMMAqua) environments, Rynite� 530NC10 and BK503 and Rynite� 545 NC10 andBK504 resins maintained over 90% of their originaltensile strength and 73% of their original elongationproperties. The EMMA and EMMAqua environ-ments have similar effects on the properties of theRynite� 530 and Rynite� 545 resins. All test spec-imens had reduced gloss levels after exposure. On anaverage, samples exposed in Arizona receivedapproximately 150,000 langleys of sunlight per year.These tests correspond to about 3.3 years of naturalweathering in Arizona.22

Stabilization: See general polyester stabilizers inthe introduction of this chapter.

Manufacturers and trade names: DuPont Rynite�,DuPont Teijin Films� Mylar� and Melinex�, Mit-subishi Polyester Film Hostaphan�.

Applications and uses: bottles for soft drinks andwater, food trays for oven use, roasting bags, audio/video tapes, mechanical components.

Figure 5.70 Retention of elonga-tion after 45� south outdoor Ari-zona weathering of DuPontRynite� PET resins.24

Figure 5.71 Structure of polyethylene napthalate(PEN).

Figure 5.72 Photolysis leading to cross-linking inpoly(ethylene naphthalate).

5: POLYESTERS 141

Data for PET plastics are found in Tables5.13e5.20 and Figs 5.52e 5.70.

5.6 Polyethylene Naphthalate

Poly(ethylene 2,6-naphthalene dicarboxylate)(PEN) is the condensation product of 2,6-naph-thalene dicarboxylic acid and ethylene glycol. PENis similar to PET but has better temperature resis-tance. The structure of this polyester is shown inFig. 5.71.Weathering: The photolysis of poly(ethylene

naphthalate) leads to cross-linking of the polymer asshown in Fig. 5.72. The cross-linked structurescause severe discoloration. This is one majordifference in exposure behavior of poly(ethylenenaphthalate) when compared to most other poly-esters. The other major difference is in UV absorp-tion spectrum. PBT and PET absorb in the short UV(up to 325 nm), and PEN absorbs in the entire UVrange (290e390 nm) making it very vulnerable toradiation. Other reactions typical of polyesters alsoapply to PEN.Manufacturers and Trade names: DuPont�

Teijin Films TEONEX�, Eastman Eastar�, ShellHiPertuf.Applications and uses: plastic beer bottles, baby

food jars.Data for PEN plastics are found in Fig. 5.73.

References

1. Wypych George. Handbook of UV degradationand stabilization. ChemTec Publishing; 2011.

2. Liquid crystal polymers, machine design. PentonMedia, Inc.; 2005.

3. Vectra polymer materials. Supplier design guide(B 121 BR E 9102/014). Hoechst AG; 1991.

4. Vectra. Ticona GmbH; 2005.5. UV light stabilization of PBT. SpecialChem

S.A.; 2005.6. Weatherability of Ultradur. BASF Aktiengesell-

schaft; 2005.7. DuPont Dow Elastomers Hypalon. 2005.8. Designing with Celanex�, Vandar�, Impet�,

Riteflex� thermoplastic polyesters designmanual (PE-10). Ticona; 2009.

9. Crastin� PBT and Rynite� PET designinformation. DuPont Engineering Polymers;2000.

10. Celanex thermoplastic polyester properties andprocessing (CX-1A). Supplier design guide(HCER 91-343/10M/692). Hoechst CelaneseCorporation; 1992.

11. Ixef reinforced polyarylamide based thermo-plastic compounds technical manual. Supplierdesign guide (Br 1409c-B-2-1190). Solvay; 1990.

12. Plastics on the roof Ultramid� and Ultradur�

for solar applications. BASF Plastics; 2011.KT/K, F 204.

Figure 5.73 Yellowing of PEN andPET as measured by opticaldensity at 400 nm vs. exposuretime in SEPAP 12/24.26


13. About Novaduran. Mitsubishi EngineeringePlastics Corporation; 2011.

14. UV light stabilization of polycarbonate andblends. SpecialChem S.A.; 2005.

15. Physical properties, Calibre, Dow poly-carbonate, LG Dow polycarbonate; 2003.

16. Cloud P, Theberge J. Glass-reinforced thermo-plastics, thermal and environmental resistanceof glass reinforced thermoplastics. Suppliertechnical report. LNP Corporation; 1982.

17. Comparison of plastics used in glazing, signs,skylights and solar collector applica-tionsdTechnical Bulletin 143. Competitor’stechnical report (ADARIS 50-1037-01). Aris-tech Chemical Corporation; 1989.

18. Ardel polyarylatedThe tough weatherablethermoplastic, Supplier marketing literature(F-47141C). Union Carbide Corporation.

19. Iupilon/Novarex properties. MitsubishiEngineering-Plastics Corporation; 2010.

20. PC resin product brochure, SABIC-PLA-650.SABIC Innovative Plastics; 2008.

21. Cycoloy PC/ABS resin product brochure. GEPlastics; 2005.

22. Rynite design handbook for DuPont engineeringplastics, Supplier design guide (E-62620),DuPont Company, 1987.

23. Radulovi�c Jovan. Degradation of polyethyleneterephthalate in natural conditions. Sci Tech Rev2006;56:45e51.

24. Rynite PET. Design guidedModule IV. DuPontEngineering Polymers; 1997.

25. Supplier technical data provided for the effect ofUV light and weather, 1st ed. 1994.

26. Scheirs J, Gardette JL. Polym Deg Stab1997;56(3):339e50.

27. Comparing the weatherability of ACRYLITESheet vs. polycarbonate sheet, CYRO Indus-tries, 2005.

5: POLYESTERS 143

6 Polyimides

This chapter covers a series of plastics of whichthe imide group is an important part of the molecule.The imide group is formed by a condensation reac-tion of an aromatic anhydride group with an aromaticamine as shown in Fig. 6.1.

This group is very thermally stable. Aliphaticimides are possible, but the thermal stability isreduced, and thermal stability is one of the mainreasons to use an imide-type polymer.

6.1 Polyamide-Imide

Polyamide-imides (PAIs) are thermoplasticamorphous polymers that have useful properties:

� Exceptional chemical resistance

� Outstanding mechanical strength

� Excellent thermal stability

� Performs from cryogenic up to 260 �C

� Excellent electrical properties

The monomers used to make PAI resin are usuallya diisocyanate and an acid anhydride such as thoseshown in Fig. 6.2.

When these two types of monomers are reacted,carbon dioxide is generated along with a PAI poly-mer. The closer the monomer ratio is to 1:1, thehigher the molecular weight of the polymer shown inFig. 6.3. Other monomer combinations are shown inTables 6.1 and 6.2.

Weathering Properties: Torlon� molding poly-mers are exceptionally resistant to degradation byUV light. Torlon� 4203L resin does not degradeafter 6000 h of Weather-Ometer� exposure, which isroughly equivalent to five years of outdoor exposure.The bearing grades, such as 4301, contain graphitepowder that renders the material black and screens

Figure 6.1 Reaction of amine withanhydride to form an imide.

Figure 6.2 Chemical structures of monomer used to make polyamideeimides.




UV radiation. These grades are even more resistantto degradation due to outdoor exposure.1

Tensile bars conforming to ASTM test methodD 1708 were exposed in an Atlas Sunshine CarbonArc Weather-Ometer�. Bars were removed aftervarious exposure periods, and tensile strength andelongation were determined. The test conditionswere a black panel temperature of 145 �F (63 �C),50 percent relative humidity and an 18-min waterspray every 102 min.A possible photo-oxidation reaction is shown in

Fig. 6.22 from the section on polyimides (PIs).Manufacturers and Trade names: Solvay

Advanced Polymers Torlon�

Applications and Uses: Electrical connectors,switches and relays; thrust washers, spline liners,valve seats, bushings, bearings, wear rings, cams andother applications requiring strength at high temper-ature and resistance to wear.Data for PAI polymers are contained in Figs

6.4e6.7.

6.2 Polyetherimide

Polyetherimide (PEI) is an amorphous engineeringthermoplastic. Thermoplastic PEIs provide thestrength, heat resistance and flame retardancy oftraditional PIs with the ease of simple melt processingseen in standard injection-molding resins like poly-carbonate and Acrylonitrile Butadiene Styrene (ABS).The key performance features of PEI resins

include:

� Excellent dimensional stability at high tempera-tures under load

� Smooth as-molded surfaces

� Transparency, though slightly yellow

� Good optical properties

� Very high strength and modulus

� High continuous-use temperature

� Inherent ignition resistance without the use ofadditives

� Good electrical properties with low ion content

There are several different polymers that areoffered in various PEI plastics. The structures ofthese are shown in Figs 6.8e6.13 with references toone of the product lines that utilize that molecule.The CAS number is 61128-46-9.The acid dianhydride used to make most of the

PEIs is 4,40-Bisphenol A Dianhydride (BPADA), thestructure of which is shown in Fig. 6.13.Some of the other monomers used in these PEIs

are shown in Fig. 6.14.Many products are called thermoplastic polyimide

by their manufacturer. These can usually be classi-fied as PEIs.Weathering Properties: Ultem� resin is inher-

ently resistant to UV radiation without the additionof stabilizers. Exposure to 1000 h of xenon arcWeather-Ometer� irradiation (0.35 W/m2 irradianceat 63 �C) produces a negligible change in the tensilestrength of the resin.7 The photochemistry of PEI hasbeen proposed as shown in Fig. 6.15.The products of photodegradation include aceto-

phenone, phenyl acetic acid, phenols, benzoic acid,phthalic anhydride and phthalic acid end groups;chain scission, photooxidative degradation of theisopropylidene bridge of BPA units, photooxidationof phthalimide units to phthalic anhydride endgroups, hydrolysis of phthalic anhydride end groups.Stabilization: PEI is inherently UV-resistant, but

the most important stabilizer used is triphenylphosphate.Manufacturers and Trade names: Sabic Inno-

vative Polymers Ultem�, DuPont� Vespel� andAurum�

Applications and uses: Surgical probes, pharma-ceutical process equipment manifolds, high-frequencyinsulators used in microwave communications equip-ment, clamps used to connect printed circuit boardsto video display units used in airplanes, tanks andships.Data for PEI polymers are contained in Figs

6.16e6.19.

Figure 6.3 Chemical structure of a typicalpolyamideeimide.


Table 6.1 The Polymer Units of Various AmideeImide Polymers (Refer to Fig. 6.3 for Polymer Structure)

PAI Code R1 from Acid Anhydride R2 from Diisocyanate

PAI(TMI/DPA)

PAI(TMI/HEA)

PAI(TMI/TFA)

PAI(TMI/CDA)

PAI(PMI/CDA)

6: POLYIMIDES 147

Table 6.2 The Polymer Units of Various AmideeImide Polymers (Refer to Fig. 6.3 for PolymerStructure)6

PAI Code R1 from Acid Anhydride R2 from Diisocyanate

PAP

PAO

PAM

PAD

PAT


Figure 6.4 Elongation after Atlas Sunshine Carbon ArcWeather-Ometer� exposure for Torlon� 4203L PAI.1 Note:The test conditions includedablackpanel temperatureof 145 �F (63 �C), 50% relativehumidity, andan18-minwater-spray every 102 min.

Figure 6.5 Tensile strength after Atlas Sunshine Carbon Arc Weather-Ometer� exposure for Torlon� 4203LPAI.1 Note: The test conditions included a black panel temperature of 145 �F (63 �C), 50% relative humidity,and an 18-min water spray every 102 min.

6: POLYIMIDES 149

Figure 6.6 Effect of UV light on theproperties of polyamideeimide filmsaged in the FS/BL (combination offluorescent sunlamps and UV blacklights) unit.2

Figure 6.7 Effect of Weather-Ometer� aging on property reten-tion of polyamideeimide films.2

Figure 6.8 Chemical structure ofBPADAePPD polyetherimide (Ultem�

5000 Series).


Figure 6.9 Chemical structure ofbisphenol diamine PMDA polyetheri-mide (Aurum�, Vespel� TP-8000Series).

Figure 6.10 Chemical struc-ture of BPADAeDDS polye-therimide sulfone (Ultem�

XH6050).

Figure 6.11 Chemical structure ofBPADAeMPDpolyetherimide (Ultem�

1000 Series).

Figure 6.12 Chemical structure of BPADAePMDAeMPD copolyetherimide (Ultem� 6000 Series).

6: POLYIMIDES 151

Figure 6.14 Chemical structures of other monomers used to make polyimides.

Figure 6.13 Chemical structure of BPADA monomer.


Figure 6.15 Photodegradation reactions of BPADAeMPD polyetherimide (Ultem� 1000 Series).3

Figure 6.16 Tensile strength afterXenon Arc Weather-Ometer�

exposure of Sabic InnovativePolymers Ultem� 1000 PEI.4

6: POLYIMIDES 153

Figure 6.17 Delta E for natural resins 30 kJ/day Xenon Arc UV weathering of Sabic Innovative Polymers Ultem�

PEI resins.5

Figure 6.18 Yellowness index for natural resins after 30 kJ/day Xenon Arc UV weathering of Sabic InnovativePolymers Ultem� PEI resins.5


6.3 Polyimide

PIs are high-temperature engineering polymersoriginally developed by the DuPont� Company.PIs exhibit an exceptional combination of thermalstability (>500 �C), mechanical toughness andchemical resistance. They have excellent dielectricproperties and inherently low coefficient of thermalexpansion. They are formed from diamines anddianhydrides such as those shown in Fig. 6.20.

Many other diamines and several other dianhy-drides may be chosen to tailor the final properties ofa polymer whose structure is like that shown inFig. 6.21.

Figure 6.20 Chemical structures ofmonomer used to make polyimides.

Figure 6.19 Gloss (60�) fornatural resins after 30 kJ/dayXenon Arc UV weathering of SabicInnovative Polymers Ultem� PEIresins.5

Figure 6.21 Chemical structure of a typicalpolyimide.

Figure 6.22 Photochemical oxidation of a polyimide.

6: POLYIMIDES 155

Weathering Properties: UV radiation, oxygen,and water have a degrading effect on Kapton� if it isdirectly exposed. The photooxidation chemistry ofthis is shown in Fig. 6.22. This effect is shown asa loss of elongation when Kapton� is exposed inFlorida test panels. Kapton� also shows a lossof elongation as a function of exposure time in anAtlas Weather-Ometer�. Normal room fluorescentlighting has no noticeable degrading effect onKapton�.8

UBEUpimol� R is stablewhen exposed to sunshineand UV light.9

Manufacturers and trade names: DuPont�Kapton�, UBE Industries Upilex�-S.Applications and uses: Aerospace, Flexible

Printed Circuits, Automotive, Heaters, Bar CodeLabels, Pressure Sensitive Tape, and ElectricalInsulation.Data for PI polymers are contained in Figs

6.23e6.36.

Figure 6.24 Ultimate elongationafter Atlas Weather-Ometer�

exposure of DuPont Kapton PI.8

Figure 6.23 Ultimate elongationafter Florida aging of DuPontKapton� PI Film.8


Figure 6.27 Tensile strengthretained after Sunshine Weather-Ometer� exposure for UBEUpilex� R and UBE Upilex� S PI.10

Figure 6.26 Flexural strengthretained after Sunshine Weather-Ometer� exposure for UBEUpimol� R PI.9

Figure 6.25 Ultimate elongationretained after Sunshine Weather-Ometer� exposure for UBEUpilex� R and UBE Upilex� SPI.10

6: POLYIMIDES 157

Figure 6.28 Flexural strengthretained after UV-CON exposurefor UBE Upimol� R PI.10

Figure 6.29 Effect of UV light onthe properties of polyimide filmsaged in the FS/BL unit.2

Figure 6.30 Effect of Weather-Ometer� aging on the propertyretention of polyimide films.2


Figure 6.31 Effect of UV light onthe volume resistivity of polyimidefilm aged in the FS/BL unit.2

Figure 6.32 Effect of Weather-Ometer� aging on the volumeresistivity of polyimide film.2

Figure 6.33 Effect of UV light onthe dielectric constant of polyimidefilm aged in the FS/BL unit.2

6: POLYIMIDES 159

Figure 6.34 Effect of Weather-Ometer� aging on the dielectricconstant of polyimide film.2

Figure 6.35 Effect of UV light onthe dielectric strength of polyimidefilm aged in the FS/BL unit.2

Figure 6.36 Effect of Weather-Ometer� aging on the dielectricstrength of polyimide film.2


Reference

1. Torlon polyamide-imide design guide, SolvayAdvanced Polymers. L.L.C.; 2003.

2. Alvino WM. Ultraviolet stability of polyimidesand poly amid-imides. J Appl Polym Sci 1971;15:2123e40.

3. Carroccio S, Puglisi C, Montaudo G. Photo-oxidation products of polyetherimide ULTEMdetermined by MALDI-TOF-MS. Kinetics andmechanisms.PolymDegradStab2003;80:459e76.

4. Ultem* sheet: safe and sound high performanceopaque sheet for aircraft and train interiors.SABIC Innovative Plastics; 2008.

5. SABIC e IP technical report 03-MTV-06weathering of polysulfones. Sabic InnovativePolymers; 2011.

6. Cao X, Lu F. Structure/permeability relation-ships of polyamide-imides. J Appl Polym Sci1994;54:1965e70.

7. Lexan PC. Resin brochure. GE Plastics; 2005.8. Kapton polyimide film. E.I. DuPont de Nemours;

2005.9. Upimol polyamide shape, supplier technical

report. UBE Industries.10. Supplier technical data provided for the effect of

UV light and weather. 1st ed. 1994.

6: POLYIMIDES 161

7 Polyamides Nylons

7.1 Polyamides (Nylons)

High-molecular-weight polyamides arecommonly known as nylon. Polyamides are crystal-line polymers typically produced by the condensa-tion of a diacid and a diamine. There are severaltypes and each type is often described by a number,such as nylon 66 or polyamide 66 (PA66). Thenumeric suffixes refer to the number of carbon atomspresent in the molecular structures of the amine andacid, respectively, (or a single suffix if the amine andacid groups are part of the same molecule).

The polyamide plastic materials discussed in thisbook and the monomers used to make them are givenin Table 7.1.

The general reaction is shown in Fig. 7.1.The eCOOH acid group reacts with the eNH2

amine group to form the amide. A molecule of wateris given off as the nylon polymer is formed. Theproperties of the polymer are determined by the R1

and R2 groups in the monomers. In nylon 6,6R2¼ 6C and R1¼ 4C alkanes, but one also has toinclude the two carboxyl carbons in the diacid to getthe number it designates to the chain.

The structures of these diamine monomers areshown in Fig. 7.2, and those of the diacid monomersare shown in Fig. 7.3. Figure 7.4 shows the aminoacid monomers. These structures only show thefunctional groups; the CH2 connecting groups areimplied at the bond intersections.

All polyamides tend to absorb moisture which canaffect their properties. Properties are often reportedas dry as molded or conditioned (usually at equilib-rium in 50% relative humidity at 23 �C). Theabsorbed water tends to act like a plasticizer and canhave a significant effect on the plastic’s properties.

Weathering Properties: Acid rain can lead tohydrolysis by nucleophilic substitution of amino linkin polyamides as shown in Fig. 7.5. Hydrolysis underbasic conditions may also occur as shown in Fig. 7.6.

Photolysis leads to scission of the amide linkage asshown in Figure 7.7. The radicals formed can rear-range forming small volatile molecules such ascarbon monoxide and ethylene. The radicals can alsoabstract a hydrogen from a neighboring molecule,which leads to cross-linking.

Products of photodegradation depend somewhat onthe particular polyamide but include amines, carbonmonoxide, hydrogen, hydrocarbons, cross-links,carbon dioxide, acids, aldehydes, ketones, water,ammonia, hydroperoxides, pyrrole, and ethylene.

Stabilization:Ultraviolet (UV) absorber: such as 2-benzo-

triazol-2-yl-4,6-di-tert-butylphenol.Screeners: especially carbon black.Hindered amine light stabilizers: such as 1,3,

5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)- (sold as Chimassorb 119 by Ciba/BASF)

Phenolic antioxidants: such as ethylene-bis(oxyethylene)-bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate); amines such as dibenzyl-hydroxylamine.

Optical brighteners: such as 2,20-(2,5-thio-phenediyl)bis(5-tert-butylbenzoxazole)

Table 7.1 Monomers Used to Make SpecificPolyamides/Nylons

Polyamide/NylonType

Monomers Used toMake

Nylon 6 Caprolactam

Nylon 11 Aminoundecanoic acid

Nylon 12 Aminolauric acid

Nylon 66 1,6-Hexamethylenediamine and adipic acid

Nylon Amorphous Trimethyl hexamethylenediamine and terephthalicacid

Polyphthalamide Any diamine andisophthalic acid and/orterephthalic acid

Polyacrylamide m-Xylylenediamine andadipic acid




Stabilizers may be polymerized directly into thepolyamide molecule.Graphs of multipoint properties of polyamides as

a function of temperature, moisture and other factorsare given in the following sections. Because the

polyamides do absorb water, and that affects theproperties, some of the data are dry, or better dry asmolded. Some of the data are for conditioned spec-imen; they have reached equilibrium water absorp-tion from 50% relative humidity at 23 �C.

Figure 7.1 Generalized polyamide reaction.

1,6-hexamethylene diamine 1,4-diaminobutane

Figure 7.2 Chemical structures of diamines used to make polyamides.

Figure 7.3 Chemical structures of diacids used to make polyamides.

Aminoundecanoic acid Aminolauric acid

Caprolactam

Figure 7.4 Chemical structures of amino acids used to make polyamides.


7.2 Amorphous Polyamide(Polyamide Copolymers)

Polyamide copolymers are usually designed tomake amorphous materials which give no crystal-linity to the polymer structure. One such amorphouspolyamide is Grilamid� TR55 and is a polymermade from the three monomers shown in Fig. 7.8.

Some of the characteristics of amorphousnylon are

� Crystal-clear, high optical transparency

� High mechanical stability

� High heat deflection temperature

� High impact strength

� Good chemical resistance compared to otherplastics


� Low mold shrinkage

One such amorphous nylon is shown in Fig. 7.9.The tertiary butyl group attached to the amine

molecule is bulky and disrupts this molecule’s abilityto crystallize. This particular amorphous nylon issometimes designated at nylon 6-3-T. Amorphous

Figure 7.5 Hydrolysis of the amino link under acidic conditions in a polyamide (R1 and R2 are polymer chains).

Figure 7.6 Hydrolysis of the amino link under basic conditions in a polyamide (R1 and R2 are polymer chains).

Figure 7.7 Scission of the amide linkage in polyamide as a result of photolysis (R1 and R2 are polymer chains).

Aminolauric acid/laurolactam 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane Isophthalic acid

Figure 7.8 Monomers used to make Grilamid� TR55 amorphous polyamide.

7: POLYAMIDES NYLONS 165

polymers can have properties that differ significantlyfrom crystalline types, one of which is opticaltransparency.Some of the characteristics of amorphous

nylon are:

� Crystal-clear, high optical transparency

� High mechanical stability

� High heat deflection temperature

� High impact strength

� Good chemical resistance compared to otherplastics


� Low mold shrinkage

Blending even low percentages (20%) of DuPontSelar� PA with nylon 6, nylon 66, and nylon

copolymers will result in a product that behaves likean amorphous polymer. These blends retain all theadvantages of the Selar� PA resin with some of themechanical property advantages of semicrystallinenylon.Manufacturers and trade names: DuPont�

Selar� PA, EMS Chemie Grivory G 16, GrivoryG21, Grilamid� TR.Applications and uses: used as a monolayer or as

a component of multilayer flexible in meat andcheese packages as well as rigid packaging; multi-layer or monolayer is used in transparent hollowvessels (bottles), packaging films, and deep-drawnplates.In the following figures, the following materials

are referenced:

� Grilamid� TR 55: basic grade with a balancedproperty profile

� Grilamid� TR 55 LX: tough, resistant to stresscracking

� Grilamid� TR 55 LY: impact resistant, resistant tostress cracking

� Grilamid� TR 90: extremely high dynamicstrength

� Grilamid� TR 90 UV: extremely high dynamicstrength, resistant to weathering

Data for amorphous polyamides are contained inFigs 7.10e7.18.

Figure 7.9 Chemical structure of amorphous nylon.

Figure 7.10 Change in color, DE, after Weather-Ometer� exposure of EMS Grilamid� TR 55, TR 55 LX, TR 90,and TR 90 UV Nylon 12.1


Figure 7.11 Yellow index (YI) afterweathering exposure as per ASTMD1975 for EMS Grilamid� TR 90, TR90 UV, TR 55, and TR 55 LX.2

Figure 7.12 Tensile impact strengthafter Weather-Ometer� exposure forEMS Grilamid� TR 55, TR 55 LX, andTR 55 LY nylon 12.1

Figure 7.13 Tensile impact strengthafter Weather-Ometer� exposure forEMS Grilamid� TR 90 and TR 90 UV.1


Figure 7.14 Yield strength after weath-ering exposure as per ISO 4892-2 forEMS Grilamid� TR 90, TR 90 UV, TR55, and TR 55 LX.2

Figure 7.15 Tensile strength retainedafter weathering exposure as per ISO4892-2 for EMS Grilamid� TR 90, TR90 UV, TR 55, and TR 55 LX.3

Figure 7.16 Percentage retention ofelongation at yield after weathering expo-sure as per ISO 4892-2 for EMSGrilamid� TR 90, TR 90 UV, TR 55,and TR 55 LX.2


7.3 Polyamide 6 (Nylon 6)

Nylon 6 begins as pure caprolactam which is a ringstructured molecule. This is unique in that the ring isopened and the molecule polymerizes with itself.Since caprolactam has six carbon atoms, the nylonthat is produced is called nylon 6, which is nearly thesame as nylon 66 described in Section 7.6. Thestructure of nylon 6 is shown in Fig. 7.19 below withthe repeating unit in the brackets.

Some of the characteristics of nylon 6 are:

� Outstanding balance of mechanical properties.

� Outstanding toughness in equilibrium moisturecontent.

� Outstanding chemical resistance and oilresistance.

� Outstanding wear and abrasion resistance.

� Almost all grades are self-extinguishing. Theflame-resistant grades are rated UL 94VO.

� Outstanding long-term heat resistance (at a long-term continuous maximum temperature rangingbetween 80 and 150 �C).

Figure 7.17 Percentage retention ofelongation at break after weatheringexposure as per ISO 4892-2 for EMSGrilamid� TR 90, TR 90 UV, TR 55,and TR 55 LX.2

Figure 7.18 Percentage retention ofwork to break after weathering exposureas per ISO 4892-2 for EMS Grilamid� TR90, TR 90 UV, and TR 55 LX.2

Figure 7.19 Chemical structure of nylon 6.


� Grades reinforced with glass fiber and othermaterials offer superior elastic modulus andstrength.

� Offers low gasoline permeability and outstandinggas barrier properties.

� Highest rate of water absorption and highest equi-librium water content (8% or more).

� Excellent surface finish even when reinforced.

� Poor chemical resistance to strong acids andbases.

Weathering Properties: Many BASF Ultramid�

resins are suitable for outdoor applications. Theunreinforced stabilized Ultramid� resins (i.e. thosewith the letters K and H in the nomenclature type)are extremely resistant to weathering, even if they areuncolored. The outdoor performance can be furtherimproved by the use of suitable pigments, the besteffects being achieved with carbon black. Forinstance, seats that have been produced fromUltramid� B3Kand B35K containing special UVstabilizers and have been exposed for more than10 years in an open-air stadium have remainedunbreakable, and their appearance has hardlyundergone any change.4

Thin articles for outdoor use should be producedfrom Ultramid� resins with a high carbon blackcontent (e.g. the Black 20590 and 20592 types) toensure that their strength remains undiminished.Moldings with a high proportion of carbon black canalso withstand several years of exposure to tropicalconditions.4

Housings for automobile rearview mirrors areexamples of articles that must remain attractive for

many years. In this type of application, the bestresults have been obtained with products containingspecial UV stabilizers and products with a highcarbon black content (e.g. Ultramid� B35EG3 Black20590).4

Manufacturers and trade names: BASF Ultra-mid� B, Honeywell Capran� and Aegis�; EMSGrilon� B, Ube Industries.Data for polyamide 6 plastics are found in Tables

7.2 and 7.3 and Figs 7.20e7.33.

7.4 Polyamide 11(Nylon 11)

Nylon 11 has only one monomer, amino-undecanoic acid. It has the necessary amine group onone end and the acid group on the other. It poly-merizes with itself to produce the polyamide con-taining 11 carbons between the nitrogen of the amidegroups. Its structure is shown in Fig. 7.34 and it hasa CAS number of 25035-04-5.Rilsan� PA 11 is produced from a “green” raw

materialdcastor beans.Some of the characteristics of nylon 11 are:

� Low water absorption for nylon (2.5% atsaturation)

� Reasonable UV resistance

� Higher strength

� Ability to accept high loading of fillers

� Better heat resistance than nylon 12

� More expensive than nylon 6 or nylon 6,6

� Relatively low impact strength

Table 7.2 Mechanical Properties Retained after Outdoor Weathering Exposure in Florida for BASF Capron�

Polyamide 65

Material Grade Capron� BK102 Capron� BK104 Capron� BK106

Features

NaturalResin,

UnstabilizedBlack Color,Unstabilized

Black Color, UVStabilized

Black Color, UVStabilized

Exposure Time (Days) 152 304 152 304 1217 152 304 1217 152 304 1522


Tensile Strength 80 68 87 77 70 97 94 92 103 99 98

Elongation 65 45 74 57 47 100 99 93 100 99 98

Note: (1) Product form: monofilament, 0.38 mm diameter. (2) 45� south exposure.


Table 7.3 Mechanical Properties Retained after OutdoorWeathering Exposure in California and Pennsylvania forLNP Engineering Plastics� Polyamide 66


Exposure Time(Days)

91 182 365 730 91 182 365 730




106 100 100 106

Unnotched IzodImpact Strength

99 120 92 115

Note: (1) 1% carbon black, 30% glass fiber. (2) Test: ASTM D4135.

Figure 7.20 Elongation at break afteroutdoor exposure for Ube� polyamide 6.7

Figure 7.21 Flexural modulus afteroutdoor exposure for Ube� polyamide 6.7


Figure 7.22 Notched Izod impactstrength after outdoor exposure forUbe� polyamide 6.7

Figure 7.23 Tensile strength afteroutdoor exposure for Ube� polyamide 6.7

Figure 7.24 Flexural strength at breakafter outdoor exposure in Hiratsuka,Japan, for polyamide 6.7


Figure 7.25 Flexural modulus afteroutdoor exposure in Hiratsuka, Japan,for polyamide 6.8

Figure 7.26 Notched Izod impactstrength after outdoor exposure inHiratsuka, Japan, for polyamide 6.9

Figure 7.27 Weight change afteroutdoor exposure in Hiratsuka, Japan,for polyamide 6.8


Figure 7.28 Flexural strength afteroutdoor exposure in Hiratsuka, Japan,for polyamide 6.9

Figure 7.29 Tensile strength afteroutdoor exposure in Hiratsuka, Japan,for polyamide 6.9

Figure 7.30 Elongation after sunshineWeather-Ometer� exposure of poly-amide 6.9


Figure 7.31 Tensile strength aftersunshine Weather-Ometer� exposureof polyamide 6.9

Figure 7.32 Tensile impact strengthafter weathering of EMSeGrivoryGrilon� AS polyamide 6 resins.10

Figure 7.33 Tensile impact strengthafter weathering of EMSeGrivoryGrilon� AG-30 glass-fiber-reinforcedpolyamide 6 resins.10


Weathering resistance: Parts made from Rilsan�

PA 11 perform very well in a wide variety of climatesaround the world. Rilsan� PA 11 is particularlyresistant to degradation from the combined effect ofthe sun’s rays and rainwater. The use of stabilizerpackages also helps to further increase the weath-ering resistance of natural and colored grades.Manufacturers and trade names: Arkema

Rilsan� B and Suzhou Hipro Polymers Hiprolon�.Data for polyamide 11 plastics are found in

Fig. 7.35.

7.5 Polyamide 12 (Nylon 12)

Nylon 12 has only one monomer, aminolauricacid. It has the necessary amine group on one endand the acid group on the other. It polymerizes withitself to produce the polyamide containing 12carbons between the two nitrogen atoms of the twoamide groups. Its structure is shown in Fig. 7.12.The properties of semicrystalline polyamides are

determined by the concentration of amide groups inthe macromolecules. Polyamide 12 has the lowestamide group concentration of all commerciallyavailable polyamides thereby substantiallypromoting its characteristics summarized below:

� Lowest moisture absorption (w2%): parts showlargest dimensional stability under conditions ofchanging humidity

� Exceptional impact and notched impact strength,even at temperatures well below the freezing point


Figure 7.35 Influence of the exposure site on the residual elongation at break with weathering of Rilsan�

BESNO P40TL.11

Serquigny (France): temperate and humid climate, typical of Central Europe. Bandol (France): hot and humid,typical Mediterranean climate. Iguazu (Brazil): tropical climate. Pretoria (South Africa): hot and dry climate.



� Good to excellent resistance against greases, oils,fuels, hydraulic fluids, various solvents, salt solu-tions and other chemicals

� Exceptional resistance to stress cracking,including metal parts encapsulated by injectionmolding or embedded

� Excellent abrasion resistance

� Low coefficient of sliding friction

� Noise and vibration damping properties

� Good fatigue resistance under high-frequencycyclical loading condition

� High processability

� Expensive

� Lowest strength and heat resistance of any unmod-ified generic polyamide

Weathering resistance: The influence of UVradiation causes a change in the physical and chemicalproperties of all plastics, and therefore, polyamides. Inparticular, the combination of radiation, oxygen in theair, moisture and temperature causes a reduction in theworking life of a material due to chain fission, cross-linking and other oxidation processes.

The resistance to weathering depends on thecomposition of the polymer and the kind of fillingmaterial used (glass, mineral, carbon black etc.). Thesurface of the plastic is affected first and foremost, sothat the serviceability of a part is highly dependenton its thickness.

Due to its chemical structure, Grilamid� is veryresistant to weathering and is therefore suitable for

many exterior applications. Resistance to weatheringcan be further improved by suitable UV stabilizationand pigmentation with carbon black. This allows theuse of Grilamid in applications under extremeclimates, in particular those with high UV radiation.The working life of polyamide components isdetermined both in accelerated weathering tests(filtered xenon radiation as per ISO 4892-2) and inoutdoor weathering tests (alpine climate at EMS).12

Manufacturers and trade names: ArkemaRilsan� A, EMS-Grivory� Grilamid�, Exopack�

Dartek�, Degussa Vestamid�.Data for polyamide 12 plastics are found in Figs

7.37 and 7.38.

7.6 Polyamide 66(Nylon 66)

The structure of nylon 66 is shown in Fig. 7.39.The CAS number is 32131-17-2.

Some of the characteristics of nylon 66 are:

� Outstanding balance of mechanical properties

� Outstanding toughness in equilibrium moisturecontent

� Outstanding chemical resistance and oil resistance

� Outstanding wear and abrasion resistance

� Almost all grades are self-extinguishing. Theflame-resistant grades are rated UL 94V0

� Outstanding long-term heat resistance (at a long-term continuous maximum temperature rangingbetween 80 and 150 �C)

Figure 7.37 The effect of weathering on the gloss of Grilamid� polyamide 12 resins.12


� Grades reinforced with glass fiber and other mate-rials offer superior elastic modulus and strength

� Offers low gasoline permeability and outstandinggas barrier properties

� High water absorption

� Poor chemical resistance to strong acids and bases

Weathering Properties: Nylon 66 degrades onexposure to natural and artificial weathering. Thisdegradation causes changes in its chemical, physical,and mechanical properties. The degree of changesdepends on the wavelength of the UV radiation andthe atmospheric conditions.Molded test parts exposedoutdoors to UV radiation may ultimately fail for oneof the following reasons: (1) loss of strength, (2) lossof toughness or (3) change in appearance.

Weather-resistant compositions of DuPontZYTEL� have been in service for more than20 years.13 These materials contain a grade of carbonthat has been uniformly dispersed to screen outattack by UV light.Manufacturers and trade names: Exopack

Performance Films Inc. Dartek�, DuPont� andZytel�.Data for PA66 plastics are found in Tables 7.4e7.9

and Figs 7.40e7.47.

7.7 Polyarylamide

Another partially aromatic high-performancepolyamide is polyarylamide (PAA). The primarycommercial polymer, PAMXD6, is formed bythe reaction of m-xylylenediamine and adipicacid giving the structure shown in Fig. 7.48. It isa semicrystalline polymer with the followingcharacteristics

� Very high rigidity

� High strength

Figure 7.38 The effect of weathering on the tensile impact strength of Grilamid� polyamide 12 resins.12


Table 7.4 Exposure of DuPont Minlon� 10B140 Polyamide 66 to Weather-Ometer� (Xenon Lamp)13

Exposure Time (h) 0 1000 3000 5000

Properties

Tensile strength (MPa) 98 80 77 60

Elongation (%) 3 3 3 4


Table 7.5 The Effects of Florida Weathering on the Properties of DuPont Polyamide 66 Resins13

Composition Property Units

Months

0 6 12 24 36 60 84 96 108 180

ZYTEL� 101NC010 (NotStabilized)

Yieldstress

MPa 56 (a) (a) (a) e (a) (a) (a) (a) (a)

Tensilestrength

MPa 73 37 31 31 e 23 16 19 24 24

Elongation % 300 10 6 6 e 5 5 5 e e

ZYTEL� 105BK010A (LightStabilized,Black)

Yieldstress

MPa 50 62 66 55 e 55 47 48 46 41

Tensilestrength

MPa 63 62 66 55 e 55 47 48 46 41

Elongation % 160 60 41 32 e 55 41 51 50 32(b)

ZYTEL� 101WT007 (WithTitaniumDioxide)

Yieldstress

MPa 55 43 45 45 41 e e e e e

Tensilestrength

MPa 72 61 46 45 41 e e e e e

Elongation % 205 290 230 65 30 e e e e e

MINLON�

10B140NC010

Tensilestrength

MPa 62 e 50 46

Elongation % 7 e 6 6

ZYTEL�

70G30HSLTensilestrength

MPa 125 e 112 103 100 e 97

aYield not distinguishable from tensile strength.bMaterial still tough at conclusion of test and can be bent 180� around a 3.2-mm (1/8-in.) steel mandrel.Note: Tensile bars tested as received; moisture contents ranged from 2% to 3% for ZYTEL� 101, 105 and 101 WT007.

Table 7.6 The Effects of Arizona Weathering Exposure on the Properties of DuPont Engineering PlasticsZYTEL� 101, 105 and 101 WT007 Polyamide 66 Resinsa 13


Months

0 6 12 18 24

ZYTEL� 101 NC010 (Not Stabilized) Yield stress MPa 78 e e e

Tensile strength MPa 78 31 25 45

Elongation % 55 5 5 5

ZYTEL� 101 WT007 (With TitaniumDioxide)

Yield stress MPa 81 e e e



ZYTEL� 105 BK010A (Light Stabilized,Black)

Yield stress MPa 92 90 83 88



Note: (1) After 12 months, ZYTEL� 101 and 101 WT007 show surface cracking and a broad range in tensile properties.aAll test bars exposed in dry-as-molded condition.


Table 7.7 The Effects of Moderate Climate (Delaware, USA) Weathering Exposure on the Properties of DuPontEngineering Plastics ZYTEL� 101 WT007a and 10513


Months

0 6 12 18 24

ZYTEL� 101 WT007 (With TitaniumDioxide)

Yield stress MPa 55 42 45 43 45

Tensile strength MPa 71 48 45 43 45

Elongation % 295 250 95 70 65

ZYTEL� 105 BK010A (Light Stabilized,Black)

Yield stress MPa 66 52 55 53 56

Tensile strength MPa 66 52 55 53 56

Elongation % 215 200 70 45 45aBars contained 2.5% moisture at start of test.

Table 7.8 The Effects of X-W Weather-Ometer� Exposure on the Properties of DuPont Engineering PlasticsZYTEL� 101 NC010, 101 WT007 and 10513


Hours

0 200 600 1000 2000 3000 6000

ZYTEL� 101 NC010a (notstabilized)

Yield stress MPa 54 58 b b b b b

Tensilestrength

MPa 70 62 5 42 3 39 38

Elongation % 300 310 10 10 10 10 40

ZYTEL� 101 WT007a (withtitanium dioxide)

Yield stress MPa 55 58 58 55 60 61 65

Tensilestrength

MPa 71 66 56 46 b b b

Elongation % 300 315 290 210 54 43 28

ZYTEL� 105 BK010Aa (lightstabilized, black)

Yield stress MPa 66 70 76 72 e 76 90

Tensilestrength

MPa 51 51 53 50 64 b b

Elongation % 210 105 60 46 10 14 18

ZYTEL� 408 BK010 Yield stress MPa 53 e 64 e 66 e e

Tensilestrength

MPa 59 e 64 e 66 e e

Elongation % 39 e 45 e 25 e e

ZYTEL� ST801 NC010 Yield stress MPa 41 e e 36 34 e 30

Elongation % 215 e e 59 56 e 61

ZYTEL� ST801 BK010 Tensilestrength

MPa e e e 42 39 e 37

Elongation % e e e 215 222 e 187

Note: (1) (Wetedry cycle), tensile bars 3.2 mm thick.aBased on specimens conditioned to equilibrium at 50% relative humidity.bYield not distinguishable from tensile strength.


� Very low creep

� Excellent surface finish even for a reinforcedproduct even with high glass fiber content.

� Ease of processing

� Good dimensional stability

� Slow rate of water absorption

Manufacturers and trade names: SolvayAdvanced Polymers Ixef�, Mitsubishi Gas ChemicalCo. Nylon-MXD6, Nanocor�, and Imperm�.

Applications and uses: Automotive fuel systemsand packaging.

Data for PAA plastics are found in Figs7.49e7.58.

Table 7.9 Effects of 6000 Hours of Accelerated Weathering on the Properties of Nylon 66 Resins14

Property

Nylon 6,6 Nylon 6,6

Unreinforced 33% Glass

NaturalColor

UVResistant

NaturalColor

2.0% CarbonBlack

Retention of Tensile Strength, % 22 61 58 78

Retention of Elongation atBreak, %

27 27 97 135

Retention of Tensile Modulus, % 71 67 81 87

Color Change CIELAB System

DL*a 23.6 �10.6 31.3 �9.6

Da*b �3.1 0.0 2.8 0.0

Db*c �7.6 0.6 �5.7 0.1

DE 24.9 10.6 31.9 9.6

Note: (1) Sunshine carbon arc model X-W Weather-Ometer� (wet cycle: 18 min water spray, dry cycle 102 min radiation,temperature 63 �C).aChange in luminosity (positive change indicates lightening).ba* is red to green (positive indicates closer to green).cb* is blue to yellow (positive indicates closer to yellow).

Figure 7.40 Effect of Florida weathering on the tensile strength of DuPont Engineering Plastics glass-reinforcedZytel� nylon.15

Note: Equilibrated to 50% relative humidity before testing.


Figure 7.41 Effect on Weather-Ometer�

exposure on the tensile strength ofDuPont Engineering Plastics Zytel�

70G33L nylon.15

Figure 7.42 Tensile impact strengthafter accelerated weathering of EMSeGrivory Grilon� a Polyamide 66 resins.10

Note: 1-mm-thick testing bar; xenon lampradiation with water spray cycles andtemperatures of 65�C.

Figure 7.43 Tensile impact strengthafter accelerated weathering of EMSeGrivory Grilon AG-30 glass-fiber rein-forced polyamide 66 resins.10

Note: 1-mm-thick testing bar; xenonlamp radiation with water spray cyclesand temperatures of 65 �C.


Figure 7.44 Effect of UV on tensilestrength of neat polyamide 66 resins.14

Note: Sunshine carbon arc model X-WWeather-Ometer� (wet cycle, 18 minwater spray; dry cycle, 102 min radiation;temperature 63 �C).

Figure 7.45 Effect of UV on tensilemodulus of polyamide 66 neat resins.14

Note: Sunshine carbon arc model X-WWeather-Ometer� (wet cycle: 18 minwater spray; dry cycle, 102 min radiation;temperature, 63 �C).

Figure 7.46 Effect of UV on tensilestrength of glass-reinforced polyamide66 resins.14

Note: Sunshine carbon arc model X-WWeather-Ometer� (wet cycle, 18 minwater spray; dry cycle, 102 min radiation;temperature, 63 �C).


Figure 7.47 Effect of UV on tensile modulus of glass-reinforced polyamide 66 resins.14

Note: Sunshine carbon arc model X-W Weather-Ometer� (wet cycle, 18 min water spray; dry cycle, 102 minradiation; temperature, 63 �C).

Figure 7.48 Chemical structure of PAMXD6 polyarylamide.

Figure 7.49 Flexural strength after outdoor exposure in Hiratsuka, Japan, for Solvay IXEF� 1002 and IXEF�

1022.8


Figure 7.50 Flexural modulus afteroutdoor exposure in Hiratsuka, Japan,for Solvay IXEF� 1002 and IXEF� 1022.8

Figure 7.51 Notched Izod impactstrength after outdoor exposure inHiratsuka, Japan, for Solvay IXEF�

1002 and IXEF� 1022.8

Figure 7.52 Weight change afteroutdoor exposure in Hiratsuka, Japan,for Solvay IXEF� 1002 and IXEF� 1022.8


Figure 7.53 Flexural modulus afteroutdoor exposure in Hiratsuka, Japan,for Mitsubishi Reny� MXD6 nylon.9

Figure 7.54 Notched Izod impactstrength after outdoor weathering expo-sure in Hiratsuka, Japan, for MitsubishiReny� MXD6 nylon.9

Figure 7.55 Flexural strength afteroutdoor weathering exposure inHiratsuka, Japan, for Mitsubishi Reny�

MXD6 nylon.9


Figure 7.56 Tensile strength afteroutdoor weathering exposure inHiratsuka, Japan, for Mitsubishi Reny�

MXD6 nylon.9

Figure 7.57 Elongation (%) afterSunshine Weather-Ometer� exposurein Hiratsuka, Japan, for Mitsubishi Reny�

MXD6 nylon.9

Figure 7.58 Tensile strength afterSunshine Weather-Ometer� exposurein Hiratsuka, Japan, for Mitsubishi Reny�

MXD6 nylon.9


Figure 7.59 Chemical structures of block used to make polyphthalamides.

Table 7.10 Effects of 6000 Hours of Accelerated Weathering on the Properties of Solvay Advanced PolymersAmodel� PPA Resins14

Property

Amodel� ET-1000 HS Amodel� AS-1133

Unreinforced 33% Glass

NaturalColor

0.2%CarbonBlack

2.0%CarbonBlack

NaturalColor

0.3%CarbonBlack

2.0%CarbonBlack

Retention ofTensileStrength, %

49 96 97 91 95 94

Retention ofElongation atBreak, %

8 37 50 97 104 100

Retention ofTensileModulus, %

112 112 115 106 107 104

Color ChangeCIELAB System

Delta L*a �5.4 �10.3 �15.1 2.2 �2.8 �9.4

Delta a*b �1.1 �0.4 0.0 1.1 0.1 0.0

Delta b*c 13.7 2.2 0.6 2.0 1.1 0.6

Delta E 14.8 10.5 15.1 3.1 3.0 9.4

Note: (1) Sunshine carbon arc model X-W Weather-Ometer� (wet cycle: 18 min water spray, dry cycle 102 min radiation,temperature 63 �C).aChange in luminosity (positive change indicates lightening).ba* is red to green (positive indicates closer to green).cb* is blue to yellow (positive indicates closer to yellow).


Figure 7.60 Effect of UV exposure ontensile strength of Solvay AdvancedPolymers Amodel� PPA resins.14

Note: Sunshine carbon arc model X-WWeather-Ometer� (wet cycle, 18 minwater spray; dry cycle, 102 min radiation;temperature 63 �C).

Figure 7.61 Effect of UV on tensilemodulus of Solvay Advanced PolymersAmodel� PPA resins.14


Figure 7.62 Effect of UV on tensilestrength of Solvay Advanced PolymersAmodel� glass-reinforced PPA resins.14



7.8 Polyphthalamide/High-Performance Polyamide

As a member of the nylon family, poly-phthalamide (PPA) is a semicrystalline materialformed from a diacid and a diamine. However, thediacid portion contains at least 55% terephthalic acid(TPA) or isophthalic acid (IPA). TPA and IPA arearomatic components which serve to raise themelting point and glass transition temperature andgenerally improve chemical resistance vs. standardaliphatic nylon polymers. The structure of the poly-mer depends on the ratio of the diacid ingredientsand the diamine used and varies from grade to grade.The polymer usually consists of mixtures of blocksof two or more different segments, four of which areshown in Fig. 7.59.Some of the characteristics of PPA are:

� Very high heat resistance

� Good chemical resistance

� Relatively low moisture absorption

� High strength or physical properties over a broadtemperature range

� Not inherently flame retardant

� Requires good drying equipment

� High processing temperatures

Manufacturers and trade names: SolvayAdvanced Polymers Amodel�.Applications and uses: Automotive fuel systems.

Data for PPA plastics are found in Table 7.10 andFigs 7.60e7.63.

References

1. Grilamid TR, Robert Meyer zu Westram. ADCI&O, supplier test data. September 2005.

2. EMS Grilamid TR weathering, supplier test data.July 2005.

3. Grilamid TR. A transparent polyamide withunlimited possibilities. EMS-Grivory; 2003.

4. Ultramid nylon resins product line, properties,processing. Supplier design guide (B 568/1e/4.91). BASF Corporation; 1991.

5. Capron nylon effect of exposure to sunlight.Supplier technical report (842e149). AlliedChemical; 1976.

6. Cloud P, Theberge J. Glass-reinforced thermo-plastics, thermal and environmental resistance ofglass reinforced thermoplastics. Supplier tech-nical report. LNP Corporation; 1982.

7. Ube nylon technical brochure. Supplier designguide (1989.8.1000). Ube Industries, Ltd; 1989.

8. IXEF reinforced polyarylamide based thermo-plastic compounds technical manual. Supplierdesign guide (Br 1409c-B-2-1190). Solvay;1990.


10. Grilon premium polyamide. EMSeGrivoryworldwide; 2011.

11. Rilsan. PA 11: Created from a renewablesource. Arkema; 2005.

Figure 7.63 Effect of UV on tensilemodulus of Solvay Advanced PolymersAmodel� glass-reinforced PPA resins.14



12. Grilamid polyamide 12 technical plastic forhighest demands. EMSeChemie; 2009.

13. DuPont� Minlon� and Zytel� nylon resinsdesign informationdModule II. DupontCompany; 2001.

14. AMODEL� polyphthalamide design guide.Solvay Advanced Polymers; 2003.

15. DuPont� Minlon� and Zytel� nylon resinsdesign informationdModule II. DupontCompany; 1997.


8 Polyolefins

8.1 Polyolefins

This chapter focuses on polymers made fromhydrocarbonmonomers that contain a carbonecarbondouble bond through which the polymer is made byaddition polymerization as discussed in Section 1.1.1.An alkene, also called an olefin, is a chemicalcompound made of only carbon and hydrogen atomscontaining at least one carbon-to-carbon double bond.The simplest alkenes, with only one double bond andno other functional groups, form a homologous seriesof hydrocarbons with the general formula CnH2n. Thetwo simplest alkenes of this series are ethylene andpropylene. When these are polymerized, they formpolyethylene (PE) and polypropylene (PP), which aretwo of the plastics discussed in this chapter. A slightlymore complex alkene is 4-methylpentene-1, the basisof poly(methylpentene), known under the trade nameof TPX�.

The structures of some of these monomers areshown in Fig. 8.1. Structures of the polymers may befound in the appropriate sections containing the datafor those materials.

8.2 Polyethylene

PE can be made in a number of ways. The way it isproduced can affect its physical properties. It can

also have very small amounts of comonomers, whichwill alter its structure and properties.

The basic types or classifications of PE, accordingthe ASTM D1248d12 Standard Specification forPolyethylene Plastics Extrusion Materials for Wireand Cable, are:

� Ultra low-density polyethylene, polymers withdensities ranging from 0.890 to 0.905 g per cubiccentimeter, contains comonomer;

� Very low-density polyethylene, polymers withdensities ranging from 0.905 to 0.915 g per cubiccentimeter, contains comonomer;

� Linear low-density polyethylene (LLDPE), poly-mers with densities ranging from 0.915 to 0.935 gper cubic centimeter, contains comonomer;

� Low-density polyethylene (LDPE), polymers withdensities ranging from about 0.915 to 0.935 g percubic centimeter;

� Medium-density polyethylene, polymers withdensities ranging from 0.926 to 0.940 g per cubiccentimeter, may or may not contain comonomer;and

� High-density polyethylene (HDPE), polymerswith densities ranging from 0.940 to 0.970 g percubic centimeter, may or may not containcomonomer.

Additionally, ultrahigh molecular weight poly-ethylene (UHMWPE) typically has a molecularweight 10 times that of HDPE.

Figure 8.2 shows the differences graphically. Thedifferences in the branches in terms of number andlength affect the density and melting points of someof the types.

Branching affects the crystallinity. A diagram ofa representation of the crystal structure of PE isshown in Fig. 8.3. One can imagine how branching inthe polymer chain can disrupt the crystalline regions.The crystalline regions are the highly ordered areasin the shaded rectangles of Fig. 8.3. A high degree ofbranching would reduce the size of the crystallineregions, which leads to lower crystallinity.

Figure 8.1 Chemical structures of some monomersused to make polyolefins.




The data tables and graphs that follow will be inthe order of the basic types or classifications of PEdescribed in the first part of this section, except thatdata on unspecified PE and data that cover the rangeof PE molecular weights will be first.Weathering: Like most other plastics, photooxi-

dation of PE proceeds by a free-radical chainmechanism. Initiation is caused by either the pres-ence of initiator or the presence of hydroperoxide.Figure 8.4 shows the initiation step. All PEs docontain some number of unsaturations (doublebonds) and they can form hydroperoxides as shownin Fig. 8.5. Decomposition of hydroperoxides leadsto the formation of other radicals, and to chainscissions and crosslinking.Typical results of photodegradation include

discoloration, surface whitening, cracks and loss ofmechanical performance.

Stabilization:Many stabilizers have been used and they are

usually concentration-dependent as shown in Fig. 8.6.Example stabilizers include:

� Ultraviolet Absorber (UVA): such as 2-hydroxy-4-octyloxy-benzophenone;

� Screeners: such as titanium dioxide, zinc oxide,and carbon black;

� Acid scavenger: such as hydrotalcite;

� Fiber: such as carbon nanotube;

� Hindered Amine Stabilizer (HAS): suchas1,3,5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-penamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-; sold as Chimassorb� 119 byBASF

� Phenolic antioxidant: such as 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol;

� Phosphite: such as bis-(2,4-di-t-butylphenol)pentaerythritol diphosphite;

Figure 8.2 Graphical depictions of polyethylenetypes.

Figure 8.3 Graphical diagram of polyethylenecrystal structure.

Figure 8.4 Initiation step of the photooxidation in polyethylene.


� Thiosynergist: such as didodecyl-3,30-thiodipropionate;

� Quencher: such as (2,20-thiobis(4-tert-octyl-phe-nolato))-N-butylamine-nickel(II); and

� Optical brightener: such as 2,20-(2,5-thiophene-diyl)bis(5-tert-butylbenzoxazole).

8.2.1 Linear Low-DensityPolyethylene

LLDPE differs structurally from conventionalLDPE because of the absence of long-chainbranching. It is made by a polymerization processthat is initiated by transition metal catalysts, partic-ularly Ziegler or Philips type.

Manufacturers and trade names: Dow Chem-ical Dowlex�, Exopack� Sclairfilm�, ExxonMobilChemical.

Data for LLDPE plastics are found in Figs8.7e8.12.

8.2.2 Low-Density Polyethylene

Data for LDPE plastics are found in Figs8.13e8.18.

8.2.3 High-Density Polyethylene

HDPE polymers are highly crystalline, toughmaterials. High molecular weight, HDPEs (HMW-HDPE) are a special class of linear resins withmolecular weights in the 200,000e500,000 range. Toobtain processability along with end-use properties,control of the molecular weight distribution is critical.Some materials are produced with “bimodal” molec-ular weight distribution to obtain the necessarybalance.

Manufacturers and trade names: DuPontTyvek�; LyondellBasell Alathon�, Petrolene;ExxonMobil� Paxon�, Pax-Plus�; Chevron Phi-lips Marlex�; NOVA Chemicals Sclair�.

Data for high-density PE plastics are found inTables 8.1e8.7 and Figs 8.19e8.33.

8.2.4 Ultrahigh Molecular WeightPolyethylene

Light and weathering resistance of semifinishedand finished products made from Ticona GUR�

UHMWPE exhibit surface embrittlement withinabout 3 months when used in outdoor applicationsunder central European climatic conditions. Through

Figure 8.5 Initiation step of the photooxidation in polyethylene.

Figure 8.6 Time of exposure in Weather-Ometer� to 50% tensile retention vs. concentration of HAS inHDPE tape.1

8: POLYOLEFINS 195

Figure 8.7 Tensile strengthretention (%) of various films ofLLDPE after natural (outdoor)weathering.2

Figure 8.8 Elongation at breakretention (%) of various films ofLLDPE after natural (outdoor)weathering.2

Figure 8.9 Variation in density ofLLDPE vs. accelerated agingduration under Weather-Ometer�

weathering conditions.3


Figure 8.10 Variation in density ofLLDPE vs. accelerated agingduration under QUV�-weatheringconditions.3

Figure 8.11 Variation in hardnessof LLDPE vs. accelerated agingduration under Weather-Ometer�


Figure 8.12 Variation in hardnessof LLDPE vs. accelerated agingduration under QUV�-weatheringconditions.3

8: POLYOLEFINS 197

Figure 8.13 Tensile strength reten-tion (%) of various films of LDPEafter natural (outdoor) weathering.2

Figure 8.14 Variation in density ofLDPE vs. accelerated aging dura-tion under Weather-Ometer�


Figure 8.15 Variation in density ofLDPE vs. accelerated aging dura-tion under QUV�-weatheringconditions.2


Figure 8.16 Variation in hardnessof LDPE vs. accelerated agingduration under Weather-Ometer�


Figure 8.17 Variation in hardnessof LDPE vs. accelerated agingduration under QUV�-weatheringconditions.2

Figure 8.18 Variation in elonga-tion at break of LDPE vs. naturaloutdoor-aging duration.2

8: POLYOLEFINS 199

Table 8.1 Tensile Strength after EMMA-Accelerated Weathering of Chevron Phillips Marlex� HDPE withChannel Black and Furnace Black4


Channel Black 2.5% 2.5% 2.5% 2.5%

Furnace Black 2.5% 2.5% 2.5% 2.5%



Tensile Strength (MPa) 27.6 27.6 27.6 27.6 27.6 27.6 27.6 27.6

Note: (1) Density 0.95 g/cm3. (2) Exposure location Phoenix, Arizona.

Table 8.2 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex� HDPE with VariousDegrees of Pigment Dispersion4


Dispersion Quality Good Good Fair Fair Poor Poor

Property Values After Exposure

Tensile Strength (MPa) 22.4 14.8 21.4 11 6.9 2.8

Note: (1) Density: 0.95 g/cm3. (2) Hydroxybenzophenone (UV absorber): 0.5%, CP Cadmium red 0.5%. (3) Test methodASTM 01499. (4) Exposure apparatus: Atlas Weather-Ometer�. (5) Exposure time (days): 83.3.

Table 8.3 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex� HDPE with UV Absorberand Various Orange Pigment Systems4


Coated MolybdateOrange Pigment

1% 2%

Lithopone OrangePigment

1% 2%

Mercadmium OrangePigment

0.5% 1% 2%


Tensile Strength(MPa)

24.1a 22.1a 17.2a 24.1a 24.1a 17.9a 6.2a 22.1a 24.1a

Note: (1) Density: 0.95 g/cm3. (2) Hydroxybenzophenone (UV absorber): 0.5%. (3) Test method ASTM 01499. (4)Exposure apparatus: Atlas Weather-Ometer�. (5) Exposure time (days): 416.7.aSpecimen type: ASTM D638, type IV; strain rate: 508 mm/min.


Table 8.4 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex� HDPE with 2% CadmiumYellow Pigment4


UV Stabilizer (HALS) Nickel complex A Nickel complex B Hindered amine light stabilizer


Tensile Strength (MPa) 2.07a 23.4a 26.2a 29a

Note: (1) Density: 0.95 g/cm3. (2) Hydroxybenzophenone (UV absorber): 0.5%, cadmium yellow pigment: 2%. (3) Testmethod ASTM 01499. (4) Exposure apparatus: Atlas Weather-Ometer�. (5) Exposure time (days): 416.7.aSpecimen type: ASTM D638, type IV; strain rate: 508 mm/min.

Table 8.5 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex� HDPE with UV Absorberand Various Yellow Pigments4


Cadmium Yellow Pigment 1% 2%

Coated Molybdate Yellow Pigment 1% 2%

Lithopone Yellow Pigment 1% 2%


Tensile Strength (MPa) 15.1a 22.8a 24.8a 24.1a 26.2a 11a

Note: (1) Density: 0.95 g/cm3. (2) Hydroxybenzophenone (UV absorber): 0.5%, cadmium yellow pigment: 2%. (3) Testmethod ASTM 01499. (4) Exposure apparatus: Atlas Weather-Ometer�. (5) Exposure time (days): 333.3.aSpecimen type ASTM D638, type IV, strain rate 508 mm/min.

Table 8.6 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex� HDPE with 2%TiO24


UV Stabilizer (HALS) Nickel complex A Nickel complex B Hindered amine light stabilizer

Exterior Grade TiO2 2% 2% 2% 2%

Exposure Conditions


Property Values After Exposure

Tensile Strength (MPa) 13.8a 26.9a 27.9a 34.1a

Note: (1) Density: 0.95 g/cm3. (2) Hydroxybenzophenone (UV absorber): 0.5%, exterior grade TiO2: 2%. (3) Test methodASTM 01499. (4) Exposure apparatus: Atlas Weather-Ometer�. (5) Exposure time (days): 333.3.aSpecimen Type ASTM D638, Type IV, strain rate 508 mm/min.

8: POLYOLEFINS 201

Table 8.7 Surface and Appearance after Accelerated Weathering of Chevron Phillips Marlex� HDPE with UVAbsorber, Various Antioxidants and Green Pigment5

FeaturesUnstabilized,Green Color

GreenColor

GreenColor

GreenColor

GreenColor

GreenColor


Ultranox 626(AntioxidantdGeneralElectric)

0.125 phr 0.125 phr

Weston 619(AntioxidantdGeneralElectric)

0.125 phr 0.125 phr

Cyasorb UV 531 (UVAbsorberdCytec)

0.125 phr 0.125 phr 0.125 phr

Exposure Conditions

Exposure Time (Days) 36 54 75 104 92 142


Visual Appearance Surfacecrazed andcracked

Surfacecrazedandcracked





Crazing Occurs at lineof exposure

Occurs atline ofexposure





Note: (1) Product form: injection-molded plaque. (2) Sample thickness (mm): 1.52. (3) Pigment: green. (4) Exposureapparatus: xenon Weather-Ometer�. (5) Exposure note: exposure time indicates time required to cause surface crazing andcracking.

Figure 8.19 Tensile strength after Arizona outdoor weathering of yellow Chevron Phillips Marlex� HDPE.4


Figure 8.20 Tensile strength afterWeather-Ometer� exposure ofyellow Chevron Phillips Marlex�

HDPE.4

Figure 8.21 Tensile strength afterWeather-Ometer� exposure of redChevron Phillips Marlex� HDPE.4

Figure 8.22 Tensile strength afterWeather-Ometer� exposure ofunstabilized red Chevron PhillipsMarlex� HDPE.4

8: POLYOLEFINS 203

Figure 8.23 Tensile strength afterWeather-Ometer� exposure oforange Chevron Phillips Marlex�

HDPE.4

Note: all contain 0.5% hydroxy-benzophenone UVA.

Figure 8.24 Tensile strength afterWeather-Ometer� exposure ofblue Chevron Phillips Marlex�

HDPE.4

Figure 8.25 Tensile strength afterWeather-Ometer� exposure ofChevron Phillips Marlex� HDPEwith 2% Zinc Oxide and 2% TiO2.

4

Note: all contain 0.5% hydroxy-benzophenone UVA.


Figure 8.26 Tensile strength afterWeather-Ometer� exposure ofChevron Phillips Marlex� HDPEwith varying concentrations ofTiO2.

4

Note: all unstabilized.

Figure 8.27 Tensile strength afterWeather-Ometer� exposure ofChevron Phillips Marlex� HDPEwith 1% TiO2 and various UVabsorbers.4

Figure 8.28 Tensile strength afterWeather-Ometer� exposure ofChevron Phillips Marlex� HDPEwith various degrees of carbonblack pigment dispersion.4

8: POLYOLEFINS 205

Figure 8.29 Variation in density ofHDPE vs. accelerated aging dura-tion under Weather-Ometer�


Figure 8.30 Variation in density ofHDPE vs. accelerated aging dura-tion under QUV�-weatheringconditions.2

Figure 8.31 Variation in hardnessof HDPE vs. accelerated agingduration under Weather-Ometer�



the addition of light stabilizers, outdoor service lifecan be extended to about 3½ years, depending on theconcentration of the UV absorber in GUR�.

If GUR� is modified with 2.5% w/w carbon black,for example, then no oxidative degradation is evidenteven after 5 years of outdoor weathering.7

Data for Ultrahigh molecular weight polyethyleneplastics is found in Fig. 8.34.

8.3 Polypropylene

The three main types of PP generally available areas follows:

� Homopolymers are made in a single reactorwith propylene and catalyst. It is the stiffest of

the three propylene types and has the highesttensile strength at yield. In the natural state(no colorant added) it is translucent and hasexcellent see-through or contact-clarity withliquids. In comparison to the other two types,it has less impact resistance, especiallybelow 0 �C.

� Random copolymers (homophasic copolymer)are made in a single reactor with a small amountof ethylene (<5%) added that disrupts the crystal-linity of the polymer allowing this type to be theclearest. It is also the most flexible with the lowesttensile strength of the three. It has better roomtemperature impact than homopolymer but sharesthe same relatively poor impact resistance at lowtemperatures.

Figure 8.32 Variation in hardnessof HDPE vs. accelerated agingduration under QUV�-weatheringconditions.2

Figure 8.33 Effect of pigmenta-tion on the UV stability measuredvia tensile strength of otherwiseunstabilized HDPE resinsexposed in Arizona.6

8: POLYOLEFINS 207

Figure 8.34 Tensile propertiesretained of by Hunan ZhongtaiSpecial Equipment Co. LtdUHMWPE fibers after aging.8

Note: Equipment: ATLAS Ci 5000;Test Standard: ISO 4892.2,102 min of light at 65 �C, followedby 18 min of spraying water withlight (40%e80% relative humidity).

� Impact copolymers (heterophasic copolymer),also known as block copolymers, are made ina two-reactor system where the homopolymermatrix is made in the first reactor and then trans-ferred to the second reactor where ethylene andpropylene are polymerized to create ethyleneepropylene rubber in the form of microscopicnodules dispersed in the homopolymer matrixphase. These nodules impart impact resistancesboth at ambient and cold temperatures to thecompound. This type has intermediate stiffnessand tensile strength and is quite cloudy. In general,the more ethylene monomer added, the greater theimpact resistance with correspondingly lowerstiffness and tensile strength.

Oriented and multilayered films of PP are alsocommon.Weathering: The two most important species of

photooxidation, carbonyls and hydroperoxides,occupy a prominent position in the degradationmechanisms of PP. Oxygen uptake to hydroperoxideby PP is a process substantially faster than PE becauseit contains tertiary hydrogens from the pendant eCH3

group. Detectable alcohols, peroxides, aldehydes,ketones, carboxylic acids and anhydrides wereformed as degradation products of PP.Typical results of photodegradation include yel-

lowing, loss of mechanical performance and surfacecracking.Stabilization:

� UVA: such as phenol, 2-(5-chloro-2H-benzotria-zole-2-yl)-6-(1,1-dimethylethyl)-4-methyl-;

� Screener: such as titanium dioxide, zinc oxideand carbon black;

� Acid neutralizer: such as hydrotalcite;

� Fiber: such as carbon nanotube;

� HAS: such as 1,3,5-triazine-2,4,6-triamine, N,N000

[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pen-tamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-;

� Phenolic antioxidant: such as 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol;

� Phosphites: such as bis-(2,4-di-t-butylphenol)pentaerythritol diphosphite;

� Thiosynergist: such as didodecyl-3,30-thiodipropionate;

� Quencher: such as (2,20-thiobis(4-tert-octyl-phe-nolato))-N-butylamine-nickel(II);

� Optical brightener: such as 2,20-(2,5-thiophene-diyl)bis(5-tert-butylbenzoxazole);

� Manufacturers and trade names: Ineos PP;LlyondellBasell Adflex�, Mophen; ExxonMobil�Bicor�, OPPalyte; Dow Chemical; Flint HillResources.

Data for PP plastics are found in Tables 8.8e8.11and Figs 8.35e8.42.

8.4 Poly-4-Methyl-1-Pentene

4-Methyl-1-Pentene based polyolefin is a light-weight, functional polymer that displays a unique


Table 8.8 Effect of Antioxidants on Outdoor Weathering in Florida and Puerto Rico of Polypropylene5

Material Composition (phr)

Calcium Stearate 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

Good-Rite 3114(AntioxidantdEmerald PolymerAdditives)

0.1 0.1 0.1

Irganox 1010 (AntioxidantdBASF) 0.08 0.08 0.08 0.08 0.08

Irganox 1076 (AntioxidantdBASF) 0.1 0.1 0.1

TBPP (Antioxidant) 0.1 0.3

Ultranox 626(AntioxidantdChemtura)

0.15 0.15 0.1 0.3

Weston 619(AntioxidantdChemtura)

0.15 0.15

Exposure Conditions

Exposure Location Puerto Rico Florida

Total Radiation (Langleys) 43,000 65,000 72,000 43,000 69,000 54,000 24,000 39,000 47,000 26,000 24,000



Note: (1) Product form 200/16 Denier Natural Multifilament Samples. (2) Total radiation is the radiation required to reach 50% retention of the initial tensile strength.

Table 8.9 Outdoor Weathering in California and Pennsylvania of Sabic InnovativePlastics LNP Glass-Reinforced Polypropylene9

Exposure Conditions

Exposure Location Los Angeles, California Philadelphia, Pennsylvania




Notched Izod-Impact Strength 100 100 91 100

Unnotched Izod-Impact Strength 108 104 121 85.7

Note: (1) Material composition: carbon black 1%, glass fiber reinforcement 30%. (2) Exposure test method ASTM D1435.

8:POLYOLEFIN

S209

Table 8.10 Effect of Stabilizers and Antioxidants on Outdoor Weathering in Puerto Rico of Polypropylene5


Calcium Stearate 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

P-EPQ (Antioxidant) 0.15

Good-Rite 3114(AntioxidantdEmeraldPolymer Additives)

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Ultranox 626(AntioxidantdChemtura)

0.15 0.1 0.1

Weston TNPP(AntioxidantdChemtura)

0.15

Weston 619(AntioxidantdChemtura)

0.15

Cyasorb UV 531 (UVAbsorberdCytecIndustries)

0.15 0.3 0.15 0.15 0.15 0.15

Tinuvin 144 (UVStabilizerdBASF)

0.4 0.3

Tinuvin 770 (HinderedAmine LightStabilizerdBASF)

0.3 0.4 0.3

Exposure Conditions

Exposure Note Total radiation is radiation required to reach 50%retention of initial tensile strength

Total radiation is radiation required to reach 70% retentionof initial tensile strength, experiment terminated due to lack

of further test samples

Total Radiation (Langleys) 48,000 59,000 93,000 113,000 55,000 59,000 176,000 >191,000 >191,000 150,000 150,000



Note: Product form 200/16 Denier Natural Multifilament Samples.

210

THEEFFECT

OFUV

LIG

HT

ANDW

EATHER

ONPLASTIC

SANDELASTOMERS

Table 8.11 Effect of ECC International Microcal Calcium Carbonate on Accelerated Weathering in QUV� ofPolypropylene10


Calcium Carbonate (Limestone) 40%

Microcal C110S (CalciumCarbonatedECC International)

40%


Da Color Change (%) �0.26 �0.2

Db Color Change (%) �0.24 0.15

DL Color Change (%) 0.38 0.55

Gloss at 60� Change (%) �0.3 �0.8

Note: (1) Exposure apparatus: QUV�, B lamps, exposure time (days) 126. (2) Exposure cycle: 4 h UV, 4 h moisture.

Figure 8.35 Outdoor exposuretime vs. chip impact strength ofFerro Corporation LPP30 calciumcarbonate filled polypropylenecopolymer.11

Figure 8.36 Outdoor exposuretime vs. delta E color change ofFerro Corporation LPP30 calciumcarbonate filled polypropylenecopolymer.11

8: POLYOLEFINS 211

Figure 8.38 Outdoor exposuretime vs. tangent modulus of FerroCorporation LPP30 calciumcarbonate filled polypropylenecopolymer.11

Figure 8.39 Outdoor exposuretime vs. tensile strength of FerroCorporation LPP30 calciumcarbonate filled polypropylenecopolymer.11

Figure 8.37 Outdoor exposuretime vs. flexural strength of FerroCorporation LPP30 calciumcarbonate filled polypropylenecopolymer.11


Figure 8.40 The variation in theelongation at break value asa function of exposure days forPP films weathered duringsummer and winter.12

Figure 8.41 The variation intensile strength as a function ofexposure days for PP films weath-ered during summer and winter.12

Figure 8.42 Surface roughnessafter 45� South Florida weatheringexposure of UV-stabilized polypro-pylene plaques.13

8: POLYOLEFINS 213

combination of physical properties and characteris-tics due to its distinctive molecular structure, whichincludes a bulky side chain as shown in Fig. 8.43.PMP possesses many characteristics inherent intraditional polyolefins such as excellent electricalinsulating properties and strong hydrolysis resis-tance. Moreover, it features low dielectric, superbclarity, transparency, gas permeability, heat andchemical resistance and release qualities.Manufacturers and trade names: Mitsui

Chemicals TPX� Opulent�, Honeywell PMP;ChevronPhillipsChemicalCompanyLLCCrystalorddiscontinued.Weathering Properties: The weatherability of

TPX� is comparablewith that of PP.AlthoughTPX�is susceptible to UV deterioration, this can be virtuallyeliminated by adding UV stabilizers (MSW 303).14

Data for PMP plastics are found in Fig. 8.44.

References

1. Gugumus F. Polym Deg Stab 1995;50:101e16.2. Basfar AA, Idriss Ali KM. Natural weathering

test for films of various formulations of low

density polyethylene (LDPE) and linear lowdensity polyethylene (LLDPE). Polym Deg Stab2006;91:437e43.

3. Gulmine JV, Janissek PR, Heise HM,Akcelrud L. Degradation profile of polyethyleneafter artificial accelerated weathering. PolymDeg Stab 2003;79:385e97.

4. Marlex polyethylene weatherability, suppliertechnical report (TIB3 (78e89 02)). Phillips 66Company; 1989.

5. Ultranox 626/626A antioxidants, supplier tech-nical report (CA-243B). General ElectricSpecialty Chemicals; 1990.

6. Marlex HDPE Product Brochure. PhillipsPetroleum; (1963).

7. GUR�, Ultra-high molecular weight poly-ethylene (PE-UHMW). Ticona; 2006.

8. Li C-S, Zhan M-S, Huang X-C, Zhou H. Degra-dation behavior of ultra-high molecular weightpolyethylene fibers under artificial acceleratedweathering. Polym Test 2012;31:938e43.

9. Cloud P Theberge J. Glass-reinforced thermo-plastics, thermal and environmental resistance of

Figure 8.43 Structure of PMP.

Figure 8.44 Izod impact strengthretained after Weather-Ometer�

exposure for Mitsui TPX� RT18polymethylpentene.15


glass reinforced thermoplastics, supplier tech-nical report. LNP Corporation; 1982.

10. Microcal Spa C110S for polypropylene, suppliertechnical report (APP033 P1). ECC Interna-tional; 1993.

11. DuPont Dow Elastomers Engage� PolyolefinElastomer. 2005.

12. Rajakumar K, Sarasvathy V, ThamaraiChelvan A, Chitra R, Vijayakumar CT. Natural

weathering studies of polypropylene. J PolymEnviron 2009;17:191e202.

13. UV light stabilization of polypropylene forautomotive. SpecialChem S.A.; 2005.

14. TPX polymethylpentene, supplier design guide(88.06.3000.Cl.). Mitsui Petrochemical Indus-tries Ltd; 1986.


8: POLYOLEFINS 215

9 Polyvinyls and Acrylics

9.1 Polyvinyls and Acrylics

This chapter focuses on polymers made frommonomers that contain a carbonecarbon doublebond through which the polymer is made by additionpolymerization as discussed in Section 2.1.1. Analkene, also called an olefin, is a chemical compoundmade of only carbon and hydrogen atoms containingat least one carbon-to-carbon double bond. Thesimplest alkenes, with only one double bond and noother functional groups, form a homologous series ofhydrocarbons with the general formula CnH2n. Thetwo simplest alkene of this series is ethylene. If oneof the hydrogens on the ethylene molecule ischanged to chlorine, the molecule is called vinylchloride, the basis of polyvinyl chloride (PVC),commonly called PVC. There are many other vinylmonomers that substitute different functional groupsonto the carbonecarbon double bond. Vinyl alcoholis a particularly important one. Acrylic polymers arealso polymerized through the carbonecarbon doublebond. Methyl methacrylate is the monomer used tomake poly(methyl methacrylate).

This chapter covers those addition polymers thatare not strictly hydrocarbons, containing only carbonand hydrogen.

9.2 EthyleneeVinyl AlcoholCopolymer

Ethyleneevinyl alcohol copolymer (EVOH) isa copolymer of ethylene and vinyl alcohol. Thestructure is shown in Fig. 9.1. These materials arehighly crystalline, and are produced with variouslevels of ethylene content.

The predominant product line is EVAL Companyof America (Kuraray) EVAL�. The general classesof the EVAL� product line are shown in Table 9.1.The films are often heat treated and oriented. Theseprocesses can dramatically affect the properties.

EVOH film has many desirable properties that aresummarized:

� Antistatic Properties: since EVOH resin is a highlyantistatic polymer, dust is prevented from buildingup on the package when used as a surface layer.

� Luster and Transparency: EVOH resins producea high gloss and low haze, resulting in outstandingclarity characteristics. The use of EVOH resin asthe outer surface of a package provides excellentsparkle for improved package appearance.

� Printability: with an eOH group in its molecularchain, the EVOH resin surface can be easilyprinted without special treatment.

� Resistance to Oil and Organic Solvents: EVOHresins resist oils and organic solvents, makingthem particularly suitable for packaging oilyfoods, edible oils, mineral oils, agricultural pesti-cides and organic solvents.

� Weather Resistance: EVOH resins display excel-lent weatherability. Even when exposed to outdoorconditions, the polymer retains its color, and doesnot yellow or become opaque. Mechanical prop-erty changes are minimal, demonstrating an over-all high resistance to weather effects.

� Permeability: EVOH resins offer outstanding gas(oxygen, carbon dioxide, nitrogen and helium)barrier properties and maintain their barrier prop-erty over a wide range of humidity. The oxygen-barrier properties of EVOH will vary according

Figure 9.1 The formation and structure of ethylene-vinyl alcohol copolymer (EVOH).




to the ethylene content in the polymer. Packagescontaining EVOH resins can effectively retainfragrances and preserve the aroma of the contentswithin the package. At the same time, undesirableodors are prevented from entering or leaving thepackage.

Weather Resistance: EVAL� resins displayexcellent weatherability. Even when exposed tooutdoor conditions, the polymer retains its color,does not yellow or become opaque. Mechanicalproperty changes are minimal, demonstrating anoverall high resistance to weather effects.1

Kuraray R&D center has studied the UV-resis-tance or weatherability of EVAL� films incomparison with other polymers.The following properties were examined:

� The evolution of the film appearance after outdoorexposure;

� The evolution of the permeability to helium versusthe time of exposure;

� The retention of the tensile strength versus thetime of exposure; and

� The retention of the elongation at break versus thetime of exposure.

The results indicate that EVAL� resins displayexcellent UV-resistance. Even when exposed tooutdoor conditions, the polymer retains its color. Itwill not turn yellow or become opaque. Mechanicalproperty changes are minimal, demonstrating anoverall high resistance to weather effects.Manufacturers and trade names: EVAL

Company of America (Kuraray) EVAL�, SoarusL.L.C Soarnol�.

9.3 Polyvinyl Chloride

PVC is a flexible or rigidmaterial that is chemicallynonreactive. Rigid PVC is easily machined, heatformed, welded and even solvent cemented. PVC canalso be machined using standard metal working toolsand finished to close tolerances and finishes withoutgreat difficulty. PVC resins are normally mixed withother additives such as impact modifiers and stabi-lizers, providing hundreds of PVC-based materialswith a variety of engineering properties.

Table 9.1 EVAL� EthyleneeVinyl Alcohol Copolymer (EVOH) Polymer Grade Series1

EVALTM

SeriesEthylene Content

(mol%) General Characteristics

L Series 27 Has the lowest ethylene content of any EVOH, and is suitable asan ultra high-barrier grade in several applications.

F Series 32 Offers superior barrier performance and is widely used forautomotive, bottle, film, tube and pipe applications.

T Series 32 Specially developed to obtain good layer distribution inthermoforming, and has become the industry standard formultilayer sheet applications.

J Series 32 Offers thermoforming results even superior to those of T, andcan be used for unusually deep-draw or sensitive sheet-basedapplications.

H Series 38 Has a balance between high barrier properties and long-termrun stability. Especially suitable for blown film, special "U"versions exist to allow improved processing and longer runningtimes even on less sophisticated machines.

E Series 44 Has a higher ethylene content that allows for greater flexibilityand even easier processing. Different versions have beenespecially designed for cast and blown films as well as for pipe.

G Series 48 Has the highest ethylene content, making it the best candidatefor stretch and shrink film applications.


There are three broad classifications for rigid PVCcompounds: Type II, Chlorinated polyvinyl chloride(CPVC) and I. Type II differs from Type I due togreater impact values, but lower chemical resistance.CPVC has greater high-temperature resistance. Thesematerials are considered “unplasticized”, because theyare less flexible than the plasticized formulations. PVChas a broad range of applications, from high-volumeconstruction related products to simple electric wireinsulation and coatings. CAS numbers are 9002-86-2,8063-94-3, 51248-43-2, and 93050-82-9.

Many of the ingredients contained in typical PVCformulations affect the weatherability. Some ingredi-ents have “weatherable” and “nonweatherable”grades. For example, every PVC article undergoesa certain amount of thermal degradation on the way tobecoming a finished product. The amount of thermaldegradation depends on the total heat history of theresin, frommanufacture to formulation in the extruder.PVC heat stabilizers are typically added. Tin mercap-tide heat stabilizers are commonly used for PVC-building products. The mercaptide portion of thestabilizer is detrimental to a long-term weathering ofvinyl compounds. Therefore, while it is important tohave enough stabilizer present to prevent the thermaldecomposition of the PVC resin, an excess should beavoided so that the weathering of the finished productis not affected by an excess of sulfur. Most pigmentsare defined as “weatherable” or “nonweatherable”.

Titanium dioxide, the most widely used pigment,functions also as an opacifier and, most importantly,a UV stabilizer. Impact modifiers are also classifiedas “weatherable” or “nonweatherable”. In the“weatherable” category are acrylics, modifiedacrylics and chlorinated polyethylene. In the “non-weatherable” category are methyl acrylate-buta-diene-styrene and acrylonitrile-butadiene-styreneimpact modifiers.

Weathering: Chemical structure of PVC includesthree bonds: C�H, C�Cl, and C�C. None of thesebonds can be broken by the energy of radiationpresent in the sunrays. For this reason, PVC is knownto be one of more stable polymers in outdoor use.However, PVC is still affected by sunlight exposure.A big reason for this is PVC materials are damagedby processing, mostly by heat used to mold orextrude. The severity of the processing conditionsdetermines the extent of material damage. Heat canlead to dehydrochlorination, which can lead to theformation of single and conjugated double bonds ofvarious lengths that depend on conditions (length and

severity of processing). This reaction is shown inFig. 9.2. Presence of oxygen during processingcontributes to further damage because it may oxidizedouble bonds, create radicals (Fig. 9.3) and thencarbonyl groups. On top of that, thermal stabilizersare added to minimize thermal decomposition andthese can become photosensitizers.

Typical results of photodegradation includechanges in molecular weight, yellowing, loss ofmechanical properties and gel formation.

Stabilization: Most important stabilizers:

� UVA: 2-hydroxy-4-octyloxybenzophenone;

� Screener: carbon black, titanium dioxide and zincoxide;

� Acid scavenger: hydrotalcite;

� HAS: 1,3,5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pentam-ethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-;

� Phenolic antioxidants: ethylene-bis(oxyethy-lene)-bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate);

� Phosphite: trinonylphenol phosphite;

� Thiosynergist: 2,20-thiodiethylene bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate];

� Optical brightener: 2,20-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole); 2,20-(1,2-ethylene-diyldi-4,1-phenylene)bisbenzoxazole;

� Manufacturing and trade names: PolyoneGeon�, Fiberloc�, VPI LLC Mirrex�;

� Applications and uses: Building siding, fenceand packaging are major markets for PVC. Rigidgrades are blown into bottles and made into sheetsfor thermoforming boxes and blister packs. Flex-ible PVC compounds are used in food packagingapplications because of their strength, transpar-ency, processability, and low raw material cost.

Figure 9.2 Dehydrochlorination of polyvinyl chlorideby heat.

9: POLYVINYLS AND ACRYLICS 219

PVC film can be used in marine/boat windows,recreational vehicle windows, tents and awningwindows, industrial curtains/enclosures, spraybooths, rack covers, weld screens and partitions,clean rooms, golf cart covers, binder covers, tagsand sign holders, menus, apparel and clothing,packaging and bags.

Data for PVC plastics are found in Table 9.2 andFigs 9.4e9.36.

9.4 Polyacrylics

While a large number of acrylic polymers aremanufactured, polymethyl methacrylate (PMMA) isby far the most common. The structure of PMMA isshown in Fig. 9.37. Nearly everyone has heard ofPlexiglas�. PMMA has two very distinct propertiesthat set the products apart from others. First, it isoptically clear and colorless. It has a light trans-mission of 92%. The 4% reflection loss at each

Figure 9.3 Radical generation in polyvinyl chloride.

Figure 9.4 Color change in milled andextruded dark-gray PVC samples weath-ered in Pennsylvania (standard system).3

Table 9.2 Impact Modifiers for PVC Can Affect the Weatherability. Base PVC Formulation for Figs 9.14e9.242

Ingredients White Almond

PVC Resin (K65) 100.00 100.00

Thermolite� 340 1.0 1.0

Calcium Stearate 1.5 1.5

Paraffin Wax (165 �F mp) 1.0 1.0

Calcium Carbonate (0.8 mm) 5.0 5.0

Titanium Dioxide 10.0 10.0

Plastistrength� 501 0.5 0.5

Impact Modifier 5.0 5.0

Almond Pigment System e 3.5


Figure 9.5 Color change with the weath-ering in Pennsylvania of milled light-gray-blue PVC samples.3

Figure 9.6 Color change with the weath-ering in South Florida of milled light-gray-blue PVC samples.3

Figure 9.7 Color change with the weath-ering in Arizona of milled light-gray-bluePVC samples.3


Figure 9.8 Color change with the weath-ering in Pennsylvania of milled dark-grayPVC samples.3

Figure 9.9 Color change with the weath-ering in South Florida of milled dark-grayPVC samples.3

Figure 9.10 Color change with theweathering in Arizona of milled dark-gray PVC samples.3


Figure 9.11 Color change with theweathering in Pennsylvania of milleddark-beige PVC samples.3

Figure 9.12 Color change with theweathering in South Florida of milleddark-beige PVC samples.3

Figure 9.13 Color change with theweathering in Arizona of milled dark-beige PVC samples.3


Figure 9.14 Yellowness index of Q-Panel QUV� UVB-313 eathering ofDurastrength� 200 vs. acrylic impactmodifier in PVC resin formulation (Table9.2).2

Note: QUV� weathering tests were per-formed on the white samples usingUVB-313 bulbs. QUV� conditions were4 h of light and 4 h of condensation.QUV� temperature was set at 50 �C.

Figure 9.16 Yellowness index of Floridaweathering of durastrength� 200 vs.acrylic impact modifier in white PVC resinformulation (Table 9.2).2

Figure 9.15 Yellowness index of QUV�

Q-panel UVB-340 weathering ofDurastrength� 200 vs. acrylic impactmodifier in PVC resin formulation (Table9.2).2

Note: QUV� weathering tests were per-formed on the white samples usingUVB-313 bulbs. QUV� conditions were4 h of light and 4 h of condensation.QUV� temperature was set at 50 �C.


Figure 9.17 Yellowness index of Floridaweathering of Durastrength� 200 vs.acrylic impact modifier in almond PVCresin formulation (Table 9.2).2

Figure 9.18 Yellowness index of NewJersey weathering of Durastrength� 200vs. acrylic impact modifier in white PVCresin formulation (Table 9.2).2

Figure 9.19 Yellowness index of NewJersey weathering of Durastrength� 200vs. acrylic impact modifier in almondPVC resin formulation (Table 9.2).2


Figure 9.20 Yellowness index of Arizona weathering of Durastrength� 200 vs. acrylic impact modifier in whitePVC resin formulation (Table 9.2).2

Figure 9.21 Yellowness index of Arizona weathering of Durastrength� 200 vs. acrylic impact modifier in almondPVC resin formulation (Table 9.2).2

Figure 9.22 Drop impact of Florida weathering of Durastrength� 200 vs. acrylic impact modifier in white PVCresin formulation (Table 9.2).2


Figure 9.23 Drop impact of New Jersey weathering of Durastrength� 200 vs. acrylic impact modifier in whitePVC resin formulation (Table 9.2).2

Figure 9.24 Drop impact of Arizona weathering of Durastrength� 200 vs. acrylic impact modifier in white PVCresin formulation (Table 9.2).2

Figure 9.25 Color change vs. QUV� exposure of beige Jain EX-CEL� PVC foam sheet.4


Figure 9.26 Color change vs. QUV� exposure of black Jain EX-CEL� PVC foam sheet.4

Figure 9.27 Color change vs. QUV� exposure of gold Jain EX-CEL� PVC foam sheet.4

Figure 9.28 Color change vs. QUV� exposure of gray Jain EX-CEL� PVC foam sheet.4


Figure 9.29 Color change vs. QUV� exposure of green Jain EX-CEL� PVC foam sheet.4

Figure 9.30 Color change vs. QUV� exposure of orange Jain EX-CEL� PVC foam sheet.4

Figure 9.31 Color change vs. QUV� exposure of red Jain EX-CEL� PVC foam sheet.4


Figure 9.32 Color change vs. QUV� exposure of royal blue Jain EX-CEL� PVC foam sheet.4

Figure 9.33 Color change vs. QUV� exposure of ruby red Jain EX-CEL� PVC foam sheet.4

Figure 9.34 Color change vs. QUV� exposure of sky blue Jain EX-CEL� PVC foam sheet.4


surface in unavoidable. Second, its surface isextremely hard. They are also highly weather resis-tant. PMMA has a CAS Number of 9011-14-7.

PMMA films show very good abrasion resistance,weather resistance (with a UV absorber) and areabsolutely colorless.

Acrylic resins are available as homopolymer (pri-marily PMMA), copolymer and terpolymer. Each ofthese is discussed separately in the following sections.

Applications and uses: optical parts, display items,tube and profile extrusion, automotive rear lights anddashboard lenses, extruded sheet, copying equipmentand lighting diffusers and UV protective films forexterior laminates.

Figure 9.35 Color change vs. QUV� exposure of white Jain EX-CEL� PVC foam sheet.4

Figure 9.36 Color change vs. QUV� exposure of yellow Jain EX-CEL� PVC foam sheet.4

Figure 9.37 Structure of PMMA.


Weathering: As stated earlier, acrylic polymersmay be made from a mixture of a fairly wide varietyof monomers. The acrylic polymers all have a similarpolymer backbone chemical structure and UV lightaffects that similarly, though the pendent groups canaffect the sensitivity. The pendent groups differ foreach monomer and those may have their ownchemical response to UV light.The primary effect on the acrylic polymer back-

bone is scission as shown in Fig. 9.38.

The cleavage can also occur between theoxygen and the carbonyl, or between the oxygenand the rest of the pendant side groups generatingother radicals. In this case, these radicals mayform gaseous products such as carbon monoxide(CO) or carbon dioxide (CO2) as shown inFig. 9.39.The polymer radicals shown in the bottom of

Fig. 9.39 can cross-link as shown in Fig. 9.40,particularly if no oxygen is present.

Figure 9.38 Polymethyl methacryate chain scission as a result of UV photolysis.

Figure 9.39 Acrylic side-chain scission as a result of UV photolysis can lead to generation of small volatilemolecules.

Figure 9.40 One type of cross-linking in acrylics can occur as a result of the photolysis reactions.


The products of photodegradation include hydro-peroxides, hydroxyl groups, carbonyl groups, alde-hydes, cross-links, formaldehyde, methanol,hydrogen, CO and CO2.

Stabilization: Example stabilizers:

� UVA: 2-hydroxy-4-octyloxybenzophenone;

� Screeners: ZnO; cerium oxide, ceriumetitaniumpyrophosphate;

� HAS: bis (1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate;

� Phenolic antioxidant: isotridecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

� Optical brightener: 2,20-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole)

� Manufacturers and trade names: Lucite Inter-national, Lucite Diakon and Perspex�, EvonikIndustries LLC Plexiglas�, Acrylite�, Europlex�

and Rohaglas�, Arkema Oroglas, Rowland Tech-nologies, Inc. SolaTuf�, Mitsubishi Rayon Co.,

Ltd Shinkolite�, Altuglas International Plexiglas;Novacor.

Data for acrylic plastics are found in Tables9.3e9.5 and Figs 9.41e9.49.

9.5 Ionomers

An ionomer is a polymer that comprises repeatunits of both electrically neutral repeating units anda fraction of ionized units. Only ethylene acrylic acidcopolymer is discussed in this section.

Starting with selected various grades of copol-ymers such as ethylene/methacrylic acid, manu-facturers add zinc, sodium, lithium, magnesiumor other metal salts. Acid neutralization (forinstance of the methacrylic acid in an ethylenemethacrylic acid copolymer) results in theformation of ion clusters (hence the general term,“ionomer”) within the resulting polymer matrix.The chemical structure of this process is shown inFig. 9.50.

Table 9.3 Cyro Acrylite� General Purpose F Acrylic Sheet after Xenon Arc-Accelerated Weathering5

Features Red 2149-4 Orange 3141-5 Green 564-9

Number of years of Florida outdoor weathering exposure required for the material to undergo significantchanges in color or edge appearance

Years 3e4 1e2 0.5

Table 9.5 Cyro Acrylite� General Purpose FLW Acrylic Sheet after Xenon Arc-Accelerated Weathering5

Features Red 2130-2Dark Red2135-1

Orange3127-2

Yellow4073-8

Green5143-8

Blue6157-9

Number of years of Florida outdoor-weathering exposure required for the material to undergo significantchanges in color or edge appearance

Years 5 1e2 3 1e2 0.5 3

Table 9.4 Cyro Acrylite� General Purpose FL Acrylic Sheet after Xenon Arc-Accelerated Weathering5

Features Red 2149-4 Orange 3105-5

Number of years of Florida outdoor weathering exposure required for the material to undergo significantchanges in color or edge appearance

Years 5 3


The ionomer resins incorporate many of theperformance features of the original ethylene-basedcopolymers, such as chemical resistance, meltingrange, density and basic processing characteristics.However, with the alteration forming the ionomerresin, the performance is significantly enhanced insuch areas as:

� Low-temperature impact toughness;

� Abrasion/scuff resistant

� Chemical resistance;

� Transparency/clarity

� Melt strength;

� Direct adhesion of epoxy and polyurethanefinishes, to metal, glass and natural fibers byheat lamination.

Weathering Properties: Ionomers have poorweathering resistance and must be stabilized if theyare exposed to sunlight or outdoor weather.

Figure 9.41 Light transmission for acrylic, Cyrolon� UVP polycarbonate sheet, and polycarbonate after weath-ering exposure. Note: 1/800 sheet (nominal) EMMAQUA accelerated weathered (AZ), DSET Laboratories Inc. asper ASTM D1003.6

Figure 9.42 Yellowness index for acrylic, Cyrolon� UVP polycarbonate sheet, and polycarbonate after weath-ering exposure. Note: 1/800 sheet (nominal) EMMAQUA accelerated weathered (AZ), DSET Laboratories Inc. asper ASTM D1925.6


Figure 9.43 Percentage haze for acrylic, Cyrolon� UVP polycarbonate sheet, and polycarbonate after weath-ering exposure. Note: 1/800 sheet (nominal) EMMAQUA accelerated weathered (AZ), DSET Laboratories Inc.as per ASTM D1003.6

Figure 9.44 Haze of Plexiglas� V825 after Florida and Arizona weathering.7

Figure 9.45 Luminous transmittance of Plexiglas� V825 after Florida and Arizona weathering.7


Outdoor weathering experience has confirmed theoutstanding performance of UV-stabilized DuPontSurlyn�. Parts containing carbon black have been inservice and exposed to all types of weather for over10 years with no significant change in physicalintegrity or appearance. Other pigmented parts haveretained their physical integrity and appearance afterfive years of exposure to an Arizona environment.10

The six basic rules for UV protection inionomers are10:

1. Use zinc-type ionomers for a more stable baseand long-term performance.

2. It is essential to use antioxidants with all stabi-lizer systems.

3. Both sodium- and zinc-type ionomers may bemodified for protection from occasional expo-sure to sunlight (less than 200 h/year).

4. For maximum retention of tensile and impactproperties, a combination of an antioxidant(UV absorber) and an energy quencher mustbe used. In pigmented parts, this should notpresent any limitations in product appearance.However, in clear, transparent applications,the presence of currently recommended UV

Figure 9.46 Yellowness index of Plexiglas� V825 after Florida and Arizona weathering.7

Figure 9.47 Surface gloss of Plexiglas� V825 after Florida and Arizona weathering.7


Figure 9.48 Color change, E, after Atlas Weather-Ometer� exposure of Ineos Nova Zylar� 533 clear impactmodified UV stabilized acrylic copolymer and general purpose PMMA.8

Note: ASTM D4459-99 testing was performed in accordance with Method G155-00a (Table 9.3, Cycle #4) on anAtlas Ci65A Weather-Ometer� at a xenon irradiance of 0.30W/m2 and a black panel temperature of 55 �C.

Figure 9.49 UV transmission at 300 nm for Plexiglas� G-UVT acrylic sheet and various commercial UVTsamples as a function of UVB exposure.9

Note: Reference test method: ASTM G-154.

Figure 9.50 Structure of ethylene acrylic acid copolymer ionomers.


absorbers may create unacceptable levels ofyellowness, depending upon the partthickness.

5. When maximum retention of clarity, surfacebrilliance and absence of color formation arethe primary end-use considerations, a combi-nation of an antioxidant and an energyquencher is recommended. In this system,tensile and impact characteristics will declineto one-third the level of natural gradeproperties.

6. In either of the above cases (4 and 5), additionof 2e10 ppm of Monastral blue or violet(transparent pigment) will neutralize the obser-vation of slightly yellow tints.

Manufacturers and trade names: DuPont�Surlyn� and Bexloy� (ethylene-methacrylic acid);Exxon Iotek� (Ethylene-acrylic acid); GoodrichHycar� (butadiene-acrylic acid)-discontinued; DowAmplify� (Ethylene-acrylic acid).Data for ionomer plastics are found in Tables

9.6e9.10.

Table 9.6 Physical Properties and Visual Appearance after Florida and Arizona Outdoor Weathering for UV-Stabilized DuPont Surlyn� Ionomer10

GradeSurlyn�

9520Surlyn�

9520Surlyn�

9520Surlyn�

9520Surlyn�

9910Surlyn�

8528Surlyn�

8920

Material Composition (wt%)

Irganox�

10100.3 0.3 0.3

Santonox R 0.2 0.2 0.2 0.2

Cyasorb�

5311.0 1.0

Tinuvin�

7700.5 0.5 0.5

ArgentPigment

0.2

BlackPigment

5.0 5.0

BronzePigment

0.5

Ion type Zinc Zinc Zinc Zinc Zinc Sodium Sodium

Exposure conditions

ExposureLocation

Florida Florida Florida Florida Arizona Florida Florida

ExposureTime (Days)

1095 1825 913 913 365 1095 365


PhysicalProperties

>90 No changeapparent, butnoquantitativetest data

87 No changeapparent, butnoquantitativetest data

No changeapparent, butnoquantitativetest data

No changeapparent, butnoquantitativetest data

50

Surface and appearance

VisualAppearance

Slightlydull

Slightly dull Slightlydull

Slight haze No visiblechange

Slightly dull Slighthaze

Note: (1) Irganox� 1010 (antioxidantdBASF). (2) Santonox� R (antioxidantdMonsanto). (3) Cyasorb� 531 (UVabsorberdCytec). (4) Tinuvin� 770 (hindered amine light stabilizerdBASF).


Table 9.7 Physical Properties and Visual Appearance after Accelerated Weathering in an Atlas Weather-Ometer� for Zinc Ion Type UV-StabilizedDuPont Surlyn� Ionomer10

MaterialGrade

Surlyn�

9910Surlyn�

9910Surlyn�

9910Surlyn�

9910Surlyn�

9910Surlyn�

9720 Surlyn� 9020 Surlyn� 9020Surlyn�

9020

Features Unstabilized Unstabilized


Irganox�

10100.1 0.1 0.1 0.1 0.1 0.1

Santonox R 0.2

Cyasorb�

5310.4 0.2

Tinuvin�

3280.3 0.3

Tinuvin�

7700.3 0.6 0.6 0.3 0.3 0.2

OrangePigment

0.2

SulfurPigment

2.0

Ion type Zinc Zinc Zinc Zinc Zinc Zinc Zinc Zinc Zinc

Exposure conditions

ExposureTime (Days)

125 208 125 208 125 340 42 4 42


PhysicalProperties

22 25 29 33 38 46 No changeapparent, butno quantitativetest data

No changeapparent, butno quantitativetest data

Poor


VisualAppearance

Moderatelyyellow

Slightlyyellow,slightlycrazed

Slightlyyellow


Slightlyyellow

Novisiblechange

Slightly dull No visiblechange

Yellow,crazed

Note: (1) Filtered carbon arc. (2) 60� dry, 50� wet; Irganox� 1010 (antioxidantdBASF). (3) Santonox� R (antioxidantdMonsanto). (4) Cyasorb� 531 (UVabsorberdCytec). (5) Tinuvin� 328 (UV absorberdBASF). (6) Tinuvin� 770 (hindered amine light stabilizerdBASF).

9:POLYVIN

YLS

ANDA

CRYLIC

S239

Table 9.8 Physical Properties and Visual Appearance after Accelerated Weathering in an Atlas Weather-Ometer for Zinc Ion Type UV- and Antioxidant-Stabilized, Pigmented DuPont Surlyn� 9520 Ionomer10


Irganox� 1010 0.2 0.21 0.2

Santonox R 0.2 0.2 0.2 0.2

Cyasorb� 531 1.0 0.1 1.0 1.0

Tinuvin� 770 0.2 0.1

Argent Pigment 0.2

Black Pigment 2.7 5.0

Bronze Pigment 0.5

Ion Type Zinc Zinc Zinc Zinc Zinc Zinc Zinc Zinc

Exposure Conditions

Exposure Time(Days)

292 67 58 58 58 58 67 67


Physical Properties 89 >90 100 80 100 50 No change apparent, but noquantitative test data

87


Visual Appearance Slightly dull Slightly dull Good Good Good Slightly crazed Slightly dull Slightly dull

Note: (1) Filtered carbon arc. (2) 60� dry, 50� wet. (3) Irganox� 1010 (antioxidantdBASF). (4) Santonox� R (antioxidantdMonsanto). (5) Cyasorb� 531 (UVabsorberdCytec). (6) Tinuvin� 770 (hindered amine light stabilizerdBASF).

240

THEEFFECT

OFUV

LIG

HT

ANDW

EATHER

ONPLASTIC

SANDELASTOMERS

Table 9.9 Physical Properties and Visual Appearance after Accelerated Weathering in an Atlas Weather-Ometer� for Sodium Ion Type UV- andAntioxidant-Stabilized, Pigmented DuPont Surlyn� Ionomer10

Grade

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8528

Surlyn�

8920

Surlyn�

8920

Surlyn�

8920

Surlyn�

8920

Features Unstablized Unstablized Unstablized


Lrganox

1010

0.2 0.2 0.2 0.1

Santonox R 0.2 0.2 0.2

Cyasorb�

531

1.0 0.1 02 0.2

Tinuvin�

770

0.2 0.1 0.1 1.0 1.0 0.2

Black

Pigment

5.0 2.7

Orange

Pigment

0.1 0.2

Ion Type Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium

Exposure Conditions

Exposure

Time (Days)

67 292 58 58 58 58 58 100 67 42 4 42


Physical

Properties

No change

apparent,

but no

quantitative

test data

100 100 60 65 75 25 No change

apparent,

but no

quantitative

test data

No change

apparent,

but no

quantitative

test data

No change

apparent,

but no

quantitative

test data

No change

apparent,

but no

quantitative

test data

0


Visual

Appearance

Slightly dull Slightly

dull

Yellow Good Yellow No

visible

change

Yellow,

crazed

Slight haze No visible

change

Slightly dull No visible

change

Yellow,

crazed

Note: (1) Filtered carbon arc. (2) 60� dry, 50� wet; Irganox� 1010 (antioxidantdBASF). (3) Santonox� R (antioxidantdMonsanto). (4) Cyasorb� 531(UV absorberdCytec). (5) Tinuvin� 770 (hindered amine light stabilizerdBASF).

9:POLYVIN

YLS

ANDA

CRYLIC

S241

References

1. EVAL�* Ethylene Vinyl Alcohol CopolymerExplained, EVAL� Europe. 2002.

2. Durastrength� Acrylic Impact Modifier. In:Siding topcoat and window profile yieldsmaximum impact and color retention. Arkema;2005.

3. Girois Stephane, Schipper Peggy S. Enhancedweatherability of exterior PVC building prod-ucts. Arkema Inc.; 900 First Ave King PrussiaPA, 19406; 2004.

4. PVC sheets weatherability. Jain Americas, Inc.;2008.

5. Acrylite� GP acrylic sheet fluorescent colorsand weatherability. CYRO Industries; 2005.

6. Comparing the weatherability of Acrylite sheetvs. polycarbonate sheet. CYRO Industries; 2005.

7. Plexiglas� acrylic molding resin. The ArkemaGroup; 2005.

8. UV stability of NAS� And ZYLAR�. NovaChemicals; 2005.

9. Plexiglas� G-UVT high ultraviolet (UV) trans-mitting cell cast acrylic sheet, Altuglas Inter-national. Arkema; 2005.

10. Resistance to ultraviolet irradiation for Surlynionomer resins, supplier technical report(E-78693e103520/A). DuPont Company; 1986.

Table 9.10 Physical Properties and Visual Appearance after Accelerated Weathering in a QUV� Weather-Ometer� for Zinc Ion Type DuPont Surlyn� 9910 Ionomer10

Features Unstabilized


Irganox�

10100.1 0.1 0.1 0.2 0.2 0.1 0.1

Cyasorb�

53102 0.5

Tinuvin�

3280.3

Tinuvin�

7700.3 0.2 0.2 0.2 02 0.6 0.3

Ion Type Zinc Zinc Zinc Zinc Zinc Zinc Zinc Zinc Zinc

Exposure Conditions

ExposureTime (Days)

125 125 125 83 84 83 84 125 125


PhysicalProperties

22 46 66 0 28 18 36 15 70


VisualAppearance

Moderatelyyellow

Slightlyyellow

Slighthaze

Crazed Crazed Good Good Slightlyyellow,slightlycrazed


Note: (1) Filtered carbon arc. (2) 8 h at 71 �C dry, 4 h at 48 �C wet. (3) Irganox� 1010 (antioxidantdBASF). (4) Santonox�

R (antioxidantdMonsanto). (5) Cyasorb� 531 (UV absorberdCytec). (6) Tinuvin� 770 (hindered amine lightstabilizerdBASF).


10 Fluoropolymers

10.1 Fluoropolymers

Traditionally, a fluoropolymer or fluoroplasticis defined as a polymer consisting of carbon(C) and fluorine (F). Sometimes these are ref-erred to as “Perfluoropolymers”, to distinguishthem from partially fluorinated polymers, fluo-roelastomers and other polymers that containfluorine in their chemical structure. For example,fluorosilicone and fluoroacrylate polymers are notreferred to as fluoropolymers. The monomers

used to make the various fluoropolymers areshown in Fig. 10.1.

Details of each of the fluoropolymers are in thefollowing sections. The melting points are allcompared in Table 10.1.

10.2 Polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) polymer is anexample of a linear fluoropolymer. Its structure insimplistic form is shown in Fig. 10.2.

Tetrafluoroethylene (TFE) Ethylene

Hexafluoropropylene (HFP) Perfluoromethyl vinyl ether (MVE)

Perfluoroethyl vinyl ether (EVE) Perfluoropropyl vinyl ether (PVE)

Chlorotrifluoroethylene Vinyl fluoride (VF)

Vinylidene fluoride (VF2) 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole

Figure 10.1 Structures of many monomers used to make fluoropolymers.




Formed by the polymerization of tetrafluoro-ethylene (TFE), the (eCF2eCF2e) groups repeatmany thousands of times. The fundamental proper-ties of fluoropolymers evolve from the atomicstructure of fluorine and carbon and their covalentbonding in specific chemical structures. The back-bone is formed of carbonecarbon bonds and thependant groups are carbon-fluorine bonds. Both areextremely strong bonds. The basic properties ofPTFE stem from these two very strong chemicalbonds. The size of the fluorine atom allows theformation of a uniform and continuous coveringaround the carbonecarbon bonds and protects them

from chemical attack, thus imparting chemicalresistance and stability to the molecule. PTFE israted for use up to (260 �C). PTFE does not dissolvein any known solvent. The fluorine sheath is alsoresponsible for the low surface energy (18 dyn/cm)and low coefficient of friction (0.05e0.8, static) ofPTFE. Another attribute of the uniform fluorinesheath is the electrical inertness (or nonpolarity) ofthe PTFE molecule. Electrical fields impart onlyslight polarization in this molecule, so volume andsurface resistivity are high.The PTFE molecule is simple and is quite ordered.

This is shown in the three-dimensional models ofFigs 10.3 and 10.4. PTFE can align itself with othermolecules or other portions of the same molecule.Disordered regions are called amorphous regions.This is important because polymers with high crys-tallinity require more energy to melt. In other words,they have higher melting points. When this happens,it forms what is called a crystalline region. Crystal-line polymers have a substantial fraction of theirmass in the form of parallel, closely packed mole-cules. High molecular weight PTFE resins have highcrystallinity and therefore high melting points,typically as high as 320e342 �C (608e648 �F). Thecrystallinity of as-polymerized PTFE is typically92e98%. Further, the viscosity in the molten state(called melt creep viscosity) is so high that high

Table 10.1 Melting Point Ranges of VariousFluoroplastics

FluoroplasticMelting

Point (�C)

Polytetrafluoroethylene(PTFE)

320e340

PolyethyleneChlorotrifluoroethylene(ECTFE)

240

PolyethyleneTetrafluoroethylene (ETFE)

255e280

Fluorinated Ethylene Propylene(FEP)

260e270

Perfluoro Alkoxy (PFA)* 302e310

Perfluoro Alkoxy (MFA)** 280e290

Polychlorotrifluoroethylene(PCTFE)

210e212

Polyvinylidene Fluoride(PVDF)

155e170

THV� 115e235

HTE 155e215

*Comonomer is perfluoro propylvinylether**Comonomer is perfluoro ethylvinylether

Figure 10.2 Chemical structure of polytetrafluoro-ethylene PTFE.

Figure 10.3 Three-dimensional representation ofpolytetrafluoroethylene (PTFE). (For color versionof this figure, the reader is referred to the onlineversion of this book.)

Figure 10.4 Ball and stick three-dimensional repre-sentation of polytetrafluoroethylene (PTFE). (Forcolor version of this figure, the reader is referred tothe online version of this book.)


molecular weight PTFE particles do not flow even attemperatures above its melting point. They sintermuch like powdered metals; they stick to each otherat the contact points and combine into largerparticles.

PTFE is called a homopolymer, a polymer madefrom a single monomer. Recently, many PTFEmanufacturers have added minute amounts of othermonomers to their PTFE polymerizations to producealternate grades of PTFE designed for specificapplications. Fluoropolymer manufacturers continueto call these grades modified homopolymer at below1% by weight of comonomer. DuPont grades of thistype are called Teflon� NXT resins. Dyneon�TFM� modified PTFE incorporates less than 1% ofa comonomer perfluoropropyl vinyl ether (PPVE).Daikin’s modified grade is Polyflon� M-111. Thesemodified granular PTFE materials retain the excep-tional chemical, thermal, antistick and low-frictionproperties of conventional PTFE resin, but offersome improvements:

� Weldability

� Improved permeation resistance

� Less creep

� Smoother, less porous surfaces

� Better high-voltage insulation

The copolymers described in the next sectionscontain significantly more of the non-TFEmonomers.

Weathering: PTFE is not affected by weatheringand UV light. Higher energy electron beam orgamma radiation is necessary to affect the polymer.

Manufacturers and trade names: DuPont�Teflon� PTFE, Dyneon PTFE, Daikin Polyflon�,many others.

Applications and uses: Pipe liners, fittings,valves, pumps and other components used fortransferring aggressive, ultrapure fluids.

Data for PTFE plastics are found in Table 10.2 andFigs 10.5 and 10.6.

Table 10.2 Mechanical Properties of PTFE Film after South-Florida Exposure1

Tensile Strength (MPa) Break Elongation (%)

Years of Exposure MD TD MD TD

0 45.5 8.5 320 400

10 31.5 14.9 190 390

Property Retention (%) 69 175 59 98

Note: (1) MD, machine direction. (2) TD, transverse direction.

Figure 10.5 Dielectric constant vs. outdoor exposure time of PTFE.2

10: FLUOROPOLYMERS 245

10.3 Fluorinated EthylenePropylene

If one of the fluorine atoms on TFE is replacedwith a trifluoromethyl group (eCF3), then the newmonomer is called hexafluoropropylene (HFP).Polymerization of monomers HFP and TFE yielda fluoropolymer, Fluorinated Ethylene Propylene,called FEP. The number of HFP groups is typically13% by weight or less and its structure is shown inFig. 10.7. The CAS number for FEP is 25,067-11-2.The effect of using HFP is to put a “bump” along

the polymer chain as shown in the three-dimensionalmodels shown in Figs 10.8 and 10.9. This bumpdisrupts the crystallization of the FEP, which hasatypical as-polymerized crystallinity of 70% vs.92e98% for PTFE. It also lowers its melting point.The reduction of the melting point depends on theamount of trifluoromethyl groups added andsecondarily on the molecular weight. Most FEPresins melt around 274 �C (525 �F), although lowermelting points are possible. Even high molecularweight FEP will melt and flow. The high chemicalresistance, low surface energy and good electricalinsulation properties of PTFE are retained. Manufacturers and trade names: DuPont�

Teflon� FEP, Dyneon� THV FEP, DaikinNeoflon�.Applications and uses: Applications requiring

excellent chemical resistance, superior electricalproperties and high service temperatures. Releasefilms, tubing, cable insulation and jacketing.Data for FEP plastics are found in

Tables 10.3e10.7 and Figs 10.10e10.13.

Figure 10.6 Dissipation factor vs. outdoor exposure time of PTFE.2

Figure 10.7 Chemical structure of fluorinatedethylene propylene FEP.

Figure 10.8 Three-dimensional representation offluorinated ethylene propylene (FEP). (For colorversion of this figure, the reader is referred to theonline version of this book.)

Figure 10.9 Ball and stick three-dimensional repre-sentation of fluorinated ethylene propylene (FEP).(For color version of this figure, the reader is referredto the online version of this book.)


10.4 Perfluoro Alkoxy (PFA)

Making a more dramatic change in the side groupthan that done in making FEP, chemists put

a perfluoroalkoxy group on the polymer chain. Thisgroup is signified as eOeRf, where Rf can be anynumber of totally fluorinated carbons. The mostcommon comonomer is perfluoropropyl

Table 10.3 Mechanical Properties after 20-Year South-Florida Exposure for Two Thicknesses of FEP Film

Film Thickness (mm) Years of Exposure


Elongation atBreak (%)

Tensile Modulus(MPa)

MD TD MD TD MD TD

50 0 21.4 18.6 270 290 462 407

50 5 20 13.8 365 310 462 407

50 7 20 16.6 290 300 428 434

50 10 18.6 16.6 145 221 428 476

50 15 19.4 15.4 200 190 e e

500 0 21.4 20 470 435 496 538

500 6 20 20 580 575 476 469

500 10 20.7 17.2 515 415 455 503

500 15 25.3 25.7 330 334 e e

500 20 21.1 22.0 292 294 e e


Table 10.4 Tensile Strength and Break Elongation after 20-Year South-Florida Exposure for Two Thicknesses ofFEP Film

Film Thickness (mm) Years of Exposure

Tensile Strength(% of Initial Retained)

Break Elongation(% of Initial Retained)

MD TD MD TD

50 20 91 84 74 65

500 20 100 110 62 68


Table 10.5 Material Properties (Dielectric Strength, Tensile Strength, Elongation at Break, and MIT Flex Life) ofFEP Film after South Florida Exposure

Length ofExposure(Months)

DielectricStrength(kV/mm)

Machine Direction Transverse Direction

MIT FlexLife

(Cycles)

TensileStrength(MPa)

TensileElongation atBreak (%)

TensileStrength(MPa)

TensileElongation

(%)

0 124 18.0 295 15.9 300 24,000

3 112 18.8 305 16.8 265 16,300

6 132 19.0 310 16.9 300 24,400

12 132 15.9 280 15.0 305 17,400

Note: (1) 75 mm ¼ 0.003 in.


(eOeCF2eCF2eCF3). However, other comonomersare shown in Table 10.8.The polymers based on PPVE are called PFA and

the perfluoroalkylvinylether group is typically addedat 3.5% or less. When the comonomer is per-fluoromethyl vinyl ether the polymer is called MFA.A structure of PFA is shown in Fig. 10.14. The CASNumber of PFA using Perfluoropropyl Vinyl ether(PPVE) as comonomer is 26655-00-5.

The large side group as shown in Figs 10.15 and10.16 reduces the crystallinity drastically. Themelting point is generally between 305 and 310 �C(581e590 �F) depending on the molecular weight.The melt viscosity is also dramatically dependent onthe molecular weight. Since PFA is still per-fluorinated as with FEP the high chemical resistance,low surface energy and good electrical insulationproperties are retained.

Table 10.6 Material Properties (Tensile Strength and Elongation at Break) of FEP Film after South FloridaExposure1

Length of Exposure(Months)

Machine Direction Transverse Direction





0 19.9 306 23.9 294

6 21.1 276 18.5 279

12 19.9 285 23.2 305

Note: (1) 250 mm ¼ 0.010 in.

Table 10.7 Electrical Properties of FEP Film after South-Florida Exposure1

Length of Exposure(Months)

Dielectric Strength(kV/mm)

Dielectric Constant(1 kHz)

Dissipation Factor(1 kHz)

0 60 2.3 0.00015

6 82 2.4 0.00035

12 79 2.2 0.0002

Note: (1) 250 mm ¼ 0.010 in.

Figure 10.10 Retention of percentage elongation after outdoor exposure for DuPont FEP film.3


Figure 10.11 Retention of tensilestrength after outdoor exposure forDuPont FEP film.3

Figure 10.12 Tensile strength vs.sunshine carbon arc exposure ofNeoflon� FEP sheet4.

Figure 10.13 Elongation vs. sunshinecarbon arc exposure of Neoflon� FEPsheet.4


Solvay Solexis Hyflon� MFA and PFA aresemicrystalline fully fluorinated melt-processiblefluoropolymers. Hyflon� PFA belongs to the classof PFA (perfluoroalkoxy) having a lower meltingpoint than standard PFA grades.Manufacturers and trade names: DuPont�

Teflon�; Solvay Solexis Hyflon�; Dyneon� (a 3MCompany); Daikin.Applications and uses: Lined and coated pro-

cessing equipment, vessels and housings and highpurity chemical storage.Data for PFA plastics are found in Figs

10.17e10.19.

10.5 Polyvinyl Fluoride

Polyvinyl fluoride (PVF) is a homopolymer ofvinyl fluoride. The molecular structure of PVF isshown in Fig. 10.20.DuPont� is the only known manufacturer of this

polymer they call Tedlar�. The structure aboveshows a head-to-tail configuration of the CF mono-mer; there are no fluorines on adjacent carbons. Butin reality, vinyl fluoride polymerizes in both head-to-head and head-to-tail configurations. DuPont’scommercial PVF contains 10e12% of head-to-headand tail-to-tail units, also called inversions.6 Its CASis 24981-14-4.PVF has excellent resistance to weathering,

staining and chemical attack (except ketones andesters). It exhibits very slow burning and lowpermeability to vapor. Its most visible use is in theinteriors of the passenger compartments ofcommercial aircraft.General description: PVF is available only in

film form. DuPont� Tedlar� films are available inclear, translucent or opaque white film and in severalsurface finishes.Weathering properties: PVF has outstanding

weathering properties.7 Pigmented Tedlar�, whenproperly laminated to a variety of substrates, impartsa long service life.8

Table 10.8 Perfluoroalkoxy Comonomers

Comonomer Structure

Perfluoromethyl Vinyl Ether (PMVE) CF2]CFeOeCF3

Perfluoroethyl Vinyl Ether (PEVE) CF2]CFeOeCF2eCF3

Perfluoropropyl Vinyl Ether (PPVE) CF2]CFeOeCF2eCF2eCF3

Figure 10.14 Chemical structure of perfluoro alkoxyPFA.

Figure 10.15 Three-dimensional representation ofperfluoroalkoxy (PFA). (For color version of this figure,the reader is referred to the online version of this book.)

Figure 10.16 Ball and stick three-dimensional repre-sentation of perfluoroalkoxy (PFA). (For color versionof this figure, the reader is referred to the onlineversion of this book.)


Figure 10.17 Color change, DE, aftercarbon arc accelerated weathering(Dew cycle) for PFA and MFA.5

Figure 10.18 Tensile strength retentionafter carbon arc Weather-Ometer� accel-erated weathering (Dew cycle) for PFAand MFA.5

Figure 10.19 Elongation retention aftercarbon arc Weather-Ometer� acceler-ated weathering (Dew cycle) for PFAand MFA.5


DuPont Tedlar� PVF film has excellent resistanceto sunlight degradation, stands up well to atmo-spheric pollutants and is resistant to acid rain attackand mildew. Most airborne dirt does not adhere toTedlar� film.8

Tedlar� is available as a pigmented or near-colorless, transparent film. The pigmented films offerthe highest level of protection from UV lightdegradation, as the pigments block nearly all UVandvisible light from passing through the film. Thismeans that the materials underneath the film will notbe exposed to high-energy, destructive light.8

The transparent films are available in an enhancedUV-screening formula that blocks nearly all of theUV light up to 350 nm. These UV-absorbing filmsscreen out progressively less UV light at the lessharmful, lower energy end of the UV spectrum(350e400 nm) and block very little visible light.30

Unsupported transparent Tedlar retains at least 50%of its tensile strength after 10 years of exposure inFlorida at an angle of 45� facing south.8

Most colors exhibit no more than five NBS(National Bureau of Standards) units (modifiedAdams color coordinates) of color change after20 years of vertical, US outdoor exposure.8

Tedlar� SP films match or exceed the resistanceof high-quality plastic surfacing materials to colorfade and loss of gloss. Color retention of Tedlar�

SP films is dependent upon the color beingtested.9

High-gloss Tedlar� SP films have been found toperform similarly to original equipment manufac-turer basecoat/clearcoat paints for gloss retentionunder xenon arc weathering, and provide superiorgloss retention compared to other high-gloss films,refinish paints and coextrusions.9

Data for PVF plastics are found in Figs10.21e10.31.

10.6 Polychlorotrifluoroethylene

Polychlorotrifluoroethylene (PCTFE) is a homo-polymer of chlorotrifluoroethylene, characterized bythe following structure shown in Fig. 10.33.The addition of the one chlorine atom contrib-

utes to lowering the melt viscosity to permitextrusion and injection molding. It also contributesto the transparency, the exceptional flow and therigidity characteristics of the polymer. Fluorine isresponsible for its chemical inertness and zeromoisture absorption. Therefore, PCTFE has uniqueproperties. Its resistance to cold flow, dimensionalstability, rigidity, low gas permeability and lowmoisture absorption is superior to any other fluo-ropolymer. It can be used at low temperatures.Some products contain a small amount of acomonomer.

Figure 10.20 Structure of PVF.

Figure 10.21 Effect of UV irradiation in a QUV� Weather-Ometer� on the tensile strength of PVF.10


Figure 10.22 Effect of UV irradiation ina QUV� Weather-Ometer� on the tensilemodulus of PVF.10

Figure 10.23 Effect of UV irradiation ina QUV� Weather-Ometer� on the elon-gation at break of PVF.10

Figure 10.24 Gloss retention vs. yearsof Florida exposure of Elf Atochem PVFfilm.11


Figure 10.25 Percentage of initial prop-erties retained after South-Florida weath-ering exposure at an angle of 45� facingsouth for DuPont Tedlar� PVF film.12

Figure 10.26 Percentage gloss retentionafter South-Florida weathering exposureat an angle of 45� facing south forDuPont Tedlar� PVF film.8

Figure 10.27 Average rate of UVabsorber degradation in free-standingDuPont Tedlar� PVF film after Floridaexposure.8


Figure 10.28 Color stability of DuPontTedlar� PVF film after exposure to Atlassunshine arc Weather-Ometer� Thisshould be reference #12.Note: Colored films vary slightly in colorretention, depending on color.

Figure 10.29 Percentage of initial prop-erties retained after Atlas sunshine arcWeather-Ometer� exposure of DuPontTedlar� PVF film.12

Figure 10.30 Typical color changerange of a variety of pigmented DuPontTedlar� SP films after xenon arc expo-sure as per the SAE J1960 method.9


Manufacturers and trade names: HoneywellAclar�, Arkema Voltalef�, Daikin IndustriesNeoflon� CTFE.Data for PCTFE plastics are found in

Fig. 10.34e10.37.

10.7 Polyvinylidene Fluoride

The polymers made from 1,1-di-fluoro-ethene (orvinylidene fluoride) are known as polyvinylidenefluoride (PVDF). They are resistant to oils and fats,water and steam, and gas and odors, making them ofparticular value for the food industry. PVDF is knownfor its exceptional chemical stability and excellentresistance to ultraviolet radiation. It is used chiefly inthe production and coating of equipment used inaggressive environments, and where high levels ofmechanical and thermal resistance are required. It hasalso been used in architectural applications asa coating on metal siding where it provides excep-tional resistance to environmental exposure. Thechemical structure of PVDF is shown in Fig. 10.38.

Figure 10.31 Gloss retention of DuPontTedlar� SP film after xenon arc exposureas per the SAE J1960 method.9

Figure 10.32 Chemical structure of polychlorotri-fluoroethylene PCTFE.

Figure 10.33 Elongation retained in themachine direction after Weather-Ometer� exposure of Honeywell Aclar�

22A and Aclar� 33C PCTFE.13


Figure 10.34 Elongation retained in thetransverse direction after Weather-Ometer� exposure of Honeywell Aclar�


Figure 10.35 Tensile strength retainedin the machine direction after Weather-Ometer� exposure of Honeywell Aclar�


Figure 10.36 Tensile strength retainedin the transverse direction afterWeather-Ometer� exposure of Honey-well Aclar� 22A and Aclar� 33CPCTFE.13


It CAS number is 24937-79-9. Some products arecomonomers.The alternating CH2 and CF2 groups along the

polymer chain provide a unique polarity that influ-ences its solubility and electric properties. Atelevated temperatures, PVDF can be dissolved inpolar solvents such as organic esters and amines.This selective solubility offers a way to preparecorrosion-resistant coatings for chemical processequipment and long-life architectural finishes onbuilding panels.Key attributes of PVDF include:

� Mechanical strength and toughness

� High abrasion resistance

� High thermal stability

� High dielectric strength

� High purity

� Readily melt processible

� Resistant to most chemicals and solvents

� Resistant to ultraviolet and nuclear radiation

� Resistant to weathering

� Resistant to fungi

� Low permeability to most gases and liquids

� Low flame and smoke characteristics

Weathering properties: Transparent ArkemaKynar� films are formulated with nonmigratingorganic UV absorbers to screen natural light andprotect the substrate from UV damage.14

Manufacturers and trade names: ArkemaKynar�, Solvay Solexis Solef� and Hylar�.Data for PCTFE plastics are found in Tables

10.9e10.12 and Figs 10.39e10.46.

10.8 EthyleneeTetrafluoroethylene Copolymer

Ethyleneetetrafluoroethylene copolymer (ETFE)is a copolymer of ethylene and tetrafluoroethylene(TFE). The basic molecular structure of ETFE isshown in Fig. 10.47.It is sometimes called polyethylene tetrafluoro-

ethylene. The depicted structure in Fig. 10.47 showsalternating units of TFE and ethylene. While thiscan be readily made, many grades of ETFE vary theratio of the two monomers slightly to optimizeproperties for specific end uses. Its CAS number is25038-71-5.

Figure 10.37 Chemical structure of polyvinylidenefluoride (PVDF).

Figure 10.38 Retention of tensilestrength and elongation after Miami, Flor-ida, outdoor-weathering exposure (45�angle south) for PVDF film.5


ETFE is a fluoroplastic with excellent electricaland chemical properties. It also has excellentmechanical properties. ETFE is especially suited foruses requiring high mechanical strength, chemical,thermal and/or electrical properties. The mechanical

properties of ETFE are superior to those of PTFE andFEP. ETFE has:

� Excellent resistance to extremes of temperature,ETFE has a working temperature range of�200 �C to 150 �C;

Table 10.9 Mechanical Properties and Yellowness Index after Arizona Outdoor-Weathering Exposure for SolvaySolexis Solef� 11010 PVDF5

Exposure Time (Years) 0 0.5 1 6 9

Mechanical Properties

Tensile Impact (kJ/m2) 3410 2796 2318 2707 e

Tensile Strength at Yield (MPa) 21.5 23.3 24.7 24.1 25

Elongation at Yield (%) 21 e e 9.5 10.1

Tensile Strength at Break (MPa) 54 43.7 48.6 55.7 54.3

Elongation at Break (%) 470 374 380 410 416

Elmendorf Tear Strength (N) 2.5 1.5 1.5 3.5 3.1


Yellowness Index 1.9 4.1 3.4 1.2 4.7

Note: (1) Sample thickness (mm) 75.

Table 10.10 Surface and Appearance Properties after QUV� Accelerated Weathering Exposure (UVB-313) ofSolvay Solexis Solef� 21508 PVDF5

Exposure Time (hrs) 0 200 600 1200 2000 4000

Yellowness Index �0.9 �0.5 �0.5 �0.4 �0.4 �0.3

La 93.4 93.0 92.9 93.1 93.1 93.0

aa �1.0 �0.9 �0.9 �0.9 �0.9 �0.9

ba �0.1 0.1 0.1 0.1 0.1 0.2

Gloss at 60� 116 106 93 101 98 76

Note: (1) Exposure conditions: UVB-313, ASTM D1925.aCIE 1976 measured by HunterlabdD65/10�.

Table 10.11 Retention of Mechanical Properties after Outdoor-Weathering of ArkemaKynar� PVDF Film10


Sample Thickness (mm) 0204

Exposure Conditions

Exposure Time (Days) 6209


Tensile Strength 124a

Elongation at Break 22a

Notes: (1) Transparent film. (2) 45� angle south.aTest method: ASTM D882.


Table 10.12 Retention of Mechanical Properties after Xenon Arc Weather-Ometer� Expo-sure of PVDF15

Exposure Conditions

Exposure Time (Days) 20.8 41.6


Relative Tensile Modulus 109a 93a

Tensile Strength at Yield 117 104

Tensile Strength at Break Lost Le

Elongation at Break 77 78

Notes: (1) Sample thickness 2.03 m. (2) Specimen type: microtensile specimen to ASTM D1708.aName: relative tensile modulus; test note: not an ASTM test; strain calculated from grip separation.

Figure 10.39 Color change, DE, after Miami, Florida, outdoor-weathering exposure (45� angle south) for SolvaySolexis Hylar� 5000 PVDF pigmented coatings.5

Figure 10.40 Gloss retention after Miami, Florida, outdoor-weathering exposure (45� angle south) for SolvaySolexis Hylar� 5000 PVDF pigmented coatings.5


Figure 10.41 Gloss retention afterFlorida exposure (45� angle south) forcommercial white paints.5

Figure 10.42 Effect of UV irradiation ina QUV� Weather-Ometer� on the tensilemodulus of PVDF.10

Figure 10.43 Effect of UV irradiation ina QUV� Weather-Ometer� on the tensilestrength of PVDF.10


� Excellent chemical resistance;

� Mechanical strength ETFE is good with excellenttensile strength and elongation and has superiorphysical properties compared to mostfluoropolymers;

� With low smoke and flame characteristics, ETFEis rated 94V-0 by the Underwriters LaboratoriesInc. It is odorless and nontoxic;

� Outstanding resistance to weather and aging;

� Excellent dielectric properties; and

� Nonstick characteristics.

Manufacturers and trade names: DuPont�Tefzel�, Asahi Glass Fluon�, 3M Dyneon�.Data for ETFE plastics are found in Tables

10.13e10.16 and Figs 10.48e10.54.

10.9 EthyleneeChlorotrifluoroethyleneCopolymer

Ethyleneechlorotrifluoroethylene (ECTFE)copolymer, also called polyethylene chlorotrifluoro-ethylene or ECTFE, is a copolymer of ethylene and

Figure 10.44 Effect of UV irradiation ina QUV� Weather-Ometer� on the elon-gation of PVDF.10

Figure 10.45 Gloss retention vs. yearsof Florida exposure of Elf AtochemKynar� 500.11

Figure 10.46 Chemical structure of polyethylene tet-rafluoroethylene ETFE.


chlorotrifluoroethylene. Its CAS number is 25101-45-5. Figure 10.55 shows the molecular structure ofE-CTFE:

This simplified structure shows the ratio of themonomers being 1-1 and strictly alternating, which isthe desirable proportion. Commonly known by thetrade name, Halar�, ECTFE is an expensive, melt-processable, semicrystalline, whitish semi-opaquethermoplastic with good chemical resistance andbarrier properties. It also has good tensile and creepproperties and good high-frequency electricalcharacteristics.

Processing methods include extrusion, compres-sion molding, rotomolding, blow molding and liquidand powder coating.

Manufacturers and trade names: Solvay SolexisHalar�.

Applications and uses: chemically resistantlinings and coatings, valve and pump components,

Figure 10.47 Relative change in totaltransmission after Weather-Ometer�

exposure of ETFE.17

Note: Weather-Ometer� ci35; blackpanel: 60 �C; lamp: xenon arc; filter innerand outer: borosilicate; irradiance:0.35 W/m2, no dark cycle/no rain cycle.

Table 10.13 Accelerated Weathering of DuPontTefzel� 200 ETFE in a Weather-Ometer�16



Tensile Strength 97.6 99.8

Elongation 87.6 100.5

Note: (1) Two hour cycle: 102 min of sunshine plus18 min of sunshine and rain (rain is distilled and deionizedwater). (2) Exposure temperature 63e66 �C.

Table 10.14 ETFE Mechanical Properties afterAging 10,000 h in a Weather-Ometer�17

Property Retained (%)

Modulus 11

Yield Stress 0

Yield Strain 6

Stress at Break 12

Strain at Break 18

Table 10.15 ETFE Mechanical Properties afterAging 9000 h in a QUV�17


Modulus 11

Yield Stress 17

Yield Strain 100

Stress at Break 16

Strain at Break 9

Table 10.16 Tensile Properties of ETFE Film after 15Years Exposure in South Florida (Courtesy DuPontFluoroproducts)18

Years ofExposure

TensileStrength, MPa

BreakElongation

(%)

MD TD MD TD

0 61 63.5 418 440

15 57.6 59.5 364 370

PropertyRetained (%)

94 94 87 84


Figure 10.48 Relative change in totaltransmission after QUV�-B exposure ofETFE.17

Note: Q-UV Panel; UVB-313 nm lamps;8 h light at 70 �C; 4 h Condensation50 �C.

Figure 10.49 Retention of mechanicalproperties of Asahi Glass Fluon� ETFEfilm vs. exposure.19

Figure 10.50 Transmittance of AsahiGlass Fluon� ETFE film vs. exposure.19


Figure 10.51 Effect of UV irradiation ina QUV� Weather-Ometer� on the tensilemodulus of ETFE.10

Figure 10.52 Effect of UV irradiation ina QUV� Weather-Ometer� on the tensilestrength of ETFE.10

Figure 10.53 Effect of UV irradiation ina QUV� Weather-Ometer� on the elon-gation at break of ETFE.10


hoods, tank and filter house linings, nonwovenfiltration fibers, barrier films and release/vacuumbagging films. It is used in food processing particu-larly involving acidic food and fruit juice processing.Data for ECTFE plastics are found in Tables

10.17e10.20 and Figs 10.56e10.59.Figure 10.54 Chemical structure of polyethylenechlorotrifluoroethylene ECTFE.

Figure 10.55 Retention of tensilestrength and elongation after Miami, Flor-ida, outdoor-weathering exposure(45�angle south) for Solvay SolexisHalar� ECTFE film.21

Table 10.17 Accelerated Weathering of Solvay Solexis Halar� ECTFE in a Xenon Arc Weather-Ometer�17



Tensile Modulus 89 95

Tensile Strength at Yield 103 101

Tensile Strength at Break 97 94


Note: (1) Sample thickness 2.03 mm.

Table 10.18 Halar� ECTFE Mechanical Properties after aging 10,000 h in a Weather-Ometer�20


Modulus 36

Yield Stress 8

Yield Strain 9

Stress at Break 12

Strain at Break 16


Table 10.19 Halar� ECTFE Mechanical Properties after Aging 9000 h in a QUV�20


Modulus 8

Yield Stress 9

Yield Strain 25

Stress at Break 11

Strain at Break 4

Table 10.20 Halar� ECTFE vs. ETFE: Mechanical Properties after Aging20

Property Units

Aging Period (Months)

0 4 8 12

Yellowing Index (ASTM 1925) 1.7 2.9 2.9 3.0

Melting Temperature (DSC) �C 174 174 172 173

Tensile Yield Stress MPa 40 40 43 42

Tensile Strength at Break MPA 63 44 47 45

Elongation at Break % 520 440 320 460

Tensile Modulus MPa 1280 1490 e 1310

Tensile Impact Strength (DIN 53448) kJ/m2 450 430 600 380

Figure 10.56 Retention of tensile strength and elongation after QUV� accelerated weathering exposure, UVB-313, for Solvay Solexis Halar� ECTFE film.21


Figure 10.57 Color change, E, afterQUV� accelerated weathering exposure,UVB-313, for Solvay Solexis Halar�

ECTFE film.21

Figure 10.58 Relative change in totaltransmission after Weather-Ometer�

exposure.20

Note: Weather-Ometer� ci35; blackpanel: 60 �C; lamp: xenon arc; filter innerand outer: borosilicate; irradiance:0.35 W/m2, no dark cycle/no rain cycle.

Figure 10.59 Relative change in totaltransmission after QUV�-B exposure.20

Note: Q-UV panel; UVB-313 nm lamps;8 h light at 70 �C; 4 h condensation50 �C.


References

1. Ebnesajjad S. Fluoropolymers, vol. 2. PlasticsDesign Library, William Andrew Inc. 2003.p. 417e420.

2. The J. of Teflon�, Reprint No. 25; Apr. 10, 1965.3. Ultrason E, Ultrason S product line, properties,

processing, supplier design guide (B 602e/10.92). BASF Aktiengesellschaft; 1992.

4. Product information Neoflon� FEP pellets.Diakin Industries, LTD; 2001.

5. Solvay Solexis, supplier test data; June 2005.6. Lin FMC. Chain microstructure studies of

poly(vinyl fluoride) by high resolution NMRspectroscopy, Ph.D. dissertation. University ofAkron; 1981.

7. Fluoropolymers, All Plastics; 2005.8. Product and performance guide for Tedlar� PVF

film in the flexible sign and awning market,(12/95) 244322B. DuPont de Nemours.

9. Tedlar SP� polyvinyl fluoride film, (4/97)300131A. DuPont de Nemours.

10. Kynar polyvinylidene fluoride, supplier tech-nical report (PL705-Rev4-1-91). AtochemNorth America, Inc.; 1991.

11. Creating coatings for better buildings. ElfAtochem; 1998.

12. Tedlar chemical properties, optical propertiesand weathering performance, (10/95) 234444B.DuPont de Nemours.

13. Aclar performance films, supplier technicalreport (SFI-14 Rev. 9e89). Allied Signal Engi-neered Plastics; 1989.

14. Kynar transparent UV opaque films. Atofina;2005.

15. Thermal and other properties of Halar fluo-ropolymer, supplier technical report (GHG).Ausimont.

16. Tefzel fluropolymer design handbook, supplierdesign guide (E-31301e1). Du Pont Company;1973.

17. http://www.solvayplastics.com/sites/solvayplastics/EN/specialty_polymers/Markets/Alternative_Energy/Pages/solar-energy.aspx; 2012.

18. Ebnesajjad Sina, Khaladkar, Pradip R. Fluo-ropolymers applications in chemical processingindustriesdThe definitive user’s guide anddatabook. William Andrew Publishing/PlasticsDesign Library; 2005.

19. Asahi Glass Fluon� ETFE website.20. Solar Energy. Ajedium (Solvay); 2012.21. Halar� ECTFE ethylene-chlorotrifluoroethylene

design and processing guide. Solvay Solexis;2006.


http://www.solvayplastics.com/sites/solvayplastics/EN/specialty_polymers/Markets/Alternative_Energy/Pages/solar-energy.aspx



11 High-Temperature/High-Performance Polymers

This chapter covers several high-temperature,high-performance plastics. They might be classifiedor have been appropriate to include in anotherchapter, but they are grouped in this chapter becauseof their performance levels.

11.1 PolyarylEtherKetone

Polyaryletherketone (PAEK) is a family of semi-crystalline thermoplastics with high-temperaturestability and high mechanical strength. The structureof PAEK varies but one of which is shown inFig. 11.1. Commercial plastics that fall within thisfamily include:

� Polyetheretherketone (PEEK)

� Polyetherketone

� Polyetheretherketoneketone

� Polyetherketoneetherketoneketone

� Polyetherketoneketone

The good strength of the semicrystalline aromaticpolymers is maintained even at high temperatures. Inaddition, PAEK materials show very good impactstrength at low temperatures, high mechanicalfatigue strength, a very low tendency to creep as wellas good sliding and wear properties. The chemicalresistance is also very good. Due to their unusualcharacteristics, PAEK are used for particularlydemanding applications.

� High mechanical strength, even at hightemperatures

� Very good impact strength

� Low tendency to creep

� Good chemical resistance

� Good sliding and wear properties

� Low moisture absorption

� Good radiation resistance

� Poor resistance to weathering

PEEK is the only PAEK discussed in detail in thisbook.

PEEK are also referred to as polyketones. Themost common structure is given in Fig. 11.2.

PEEK is a thermoplastic with extraordinarymechanical properties. The Young’s modulus ofelasticity is 3.6 GPa and its tensile strength 170 MPa.PEEK is partially crystalline, melts at around 350 �Cand is highly resistant to thermal degradation. Thematerial is also resistant to both organic and aqueousenvironments, and is used in bearings, piston parts,pumps, compressor plate valves and cable insulationapplications. It is one of the few plastics compatiblewith ultrahigh vacuum applications. In summary, theproperties of PEEK include:

� Outstanding chemical resistance;

� Outstanding wear resistance;

� Outstanding resistance to hydrolysis;

� Excellent mechanical properties;

� Outstanding thermal properties;

� Very good dielectric strength, volume resistivityand tracking resistance; and

� Excellent radiation resistance.

Figure 11.1 Structure of a PAEK polymer.Figure 11.2 The structure of polyetheretherketone(PEEK).




Weathering properties: Victrex� PEEK, likemost linear polyaromatics, suffers from the effects ofUV degradation during outdoor weathering.However, testing has shown this effect to be minimalover a twelve-month period for both natural andpigmented moldings. In more extreme weatheringconditions, painting or pigmenting will protect thepolymer from excessive property degradation.Manufacturers and trade names: Victrex PLC

Victrex� and APTIV�, Greene, Tweed & Co.Arlon�, Solvay Advanced Polymers GATONE�and KetaSpire�.The data for PAEK based plastics are in Tables

11.1 and 11.2.

11.2 Polyphenylene Sulfide

Polyphenylene sulfide (PPS) is a semicrystallinematerial. It offers an excellent balance of properties,including high-temperature resistance, chemicalresistance, flowability, dimensional stability andelectrical characteristics. PPS must be filled withfibers and fillers to overcome its inherent brittleness.Because of its low viscosity, PPS can be molded withhigh loadings of fillers and reinforcements. Because

of its outstanding flame resistance, PPS is ideal forhigh-temperature electrical applications. It is unaf-fected by all industrial solvents. The structure of PPSis shown inFig. 11.3. TheCASnumber is 26125-40-6.There are several variants to regular PPS that may

be talked about by suppliers or may be seen in theliterature. There are:

� Regular PPS is of “modest”molecularweight.Mate-rials of this type are often used in coating products.

� Cured PPS is PPS that has been heated to hightemperature, above 300 �C, in the presence of airor oxygen. The oxygen causes some cross-linkingand chain extension called oxidative cross-linking.This results in some thermoset-like propertiessuch as improved thermal stability, dimensionalstability and improved chemical resistance.

� High molecular weight (HMW) linear PPS hasa molecular weight about double of that of regularPPS. The higher molecular weight improves elon-gation and impact strength.

� HMW branched PPS has higher molecular weightthan regular PPS, but it also has polymer chainbranches along the main molecule backbone.This provides improved mechanical properties.

Table 11.1 Tensile Strength Retained after United Kingdom Outdoor Weathering Exposure of Natural, Black andWhite-Pigmented Victrex� PEEK1

MaterialGrade Victrex PEEK 450G Victrex PEEK 450G Victrex PEEK 450G

Features Natural Resin Black Color White Color


BlackPigment(wt%)

1-2 1-2 1-2 1-2

WhitePigment(wt%)

1-2 1-2 1-2 1-2

Exposure Conditions

ExposureTime(Days)

91 182 273 365 91 182 273 365 91 182 273 365


TensileStrength

100.7 100.7 96.5 96.5 100.7 98.6 100 100 100 100.7 98.6 100.7


PPS properties are summarized:

� Continuous use temperature of 220 �C;

� Excellent dimensional properties;

� Transparent;

� Improved impact strength and toughness ascompared to Polyethersulfone (PES);

� Excellent hydrolytic stability;

� High stress cracking resistance;

� Good chemical resistance;

� Good surface release properties; and

� Expected continuous temperature of 180 �C.

Weathering: It should be noted that Fortron willdiscolor or show glass fibers on the surface, when itis used in outdoor conditions and exposed to ultra-violet rays or under a fluorescent lamp. As comparedwith the changes in appearance, less influences ofUV on the mechanical properties are found, so itshows mechanical properties are nearly equal tothose of unexposed materials.2

Products of photodegradation include cross-linking,chain scission and conjugated double bond formation.The molecular weight of PPS decreases on Weather-Ometer� exposure as shown in Fig. 11.4. Photo-degradation results in discoloration (yellowing).

Stabilization:

� Most important stabilizers:

� UltravioletAbsorber (UVA):benzotriazole (deriv-ative of Tinuvin� 327 in which chlorine atom isreplaced by phenylthio or phenylsulfonyl groups)

� Screener: carbon black

Stabilizers need to be used in high concentration inPPS as shown in Fig. 11.5.

Table 11.2 Tensile Strength Retained after United Kingdom Outdoor Weathering Exposure of PigmentedVictrex� PEEK1

MaterialGrade Victrex PEEK 450G Victrex PEEK 450G Victrex PEEK 450G

Features Yellow Color Green Color Blue Color


BluePigment(wt%)

1-2 1-2 1.2 1.2

GreenPigment(wt%)

1-2 1-2 1.2 1-2

YellowPigment(wt%)

1-2 1-2 1-2 1-2

Exposure Conditions

ExposureTime(Days)

91 182 273 365 91 182 273 365 91 182 273 365


TensileStrength

100 100 97.9 96.5 98.6 98.6 95.8 96.5 100.7 100 97.9 98.6

Figure 11.3 Structure of polyphenylene sulfide(PPS).

11: HIGH-TEMPERATURE/HIGH-PERFORMANCE POLYMERS 273

Manufacturers and trade names: Dinippon Ink,Chevron Phillips Ryton�, Ticona Fortron�, TorayTorelina�.Data for PPS plastics are in Tables 11.3 and 11.4

and Figures 11.6 and 11.7.

11.3 Polysulfone

Polysulfone (PSU) is a rigid, strong, tough, high-temperature amorphous thermoplastic. The structureof PSU is shown in Fig. 11.8. Its CAS number is25135-51-7.Its properties summarized:

� High thermal stability;

� High toughness and strength;

� Good environmental stress crack resistance;

� Inherent fire resistance; and

� Transparence.

Weathering: Because of the aromatic etherbackbone, PSU is susceptible to chemical degrada-tion upon outdoor exposure. Weather resistance canbe improved by the addition of carbon black.Applications of PSU involving outdoor exposureshould be evaluated individually, considering thespecific exposure conditions and the required mate-rial properties. Protective paints or coatings can beused to preserve the properties of PSU articlesexposed to direct sunlight.Manufacturers and trade names: Solvay

Advanced Polymers Udel�.

Figure 11.4 PPS weight averagemolecular weight vs. exposuretime in Weather-Ometer�.3

Figure 11.5 PPS color change atdifferent levels of UV absorber.3


Data for PSU plastics are found in Tables 11.5 and11.6 and Figs 11.9e11.12.

11.4 Polyphenylsulfone

Polyphenylsulfone (PPSU) is a rigid, strong,tough, high-temperature amorphous thermoplastic. Ithas a high heat deflection temperature of 405 �F(207 �C), it can withstand continuous exposure toheat and still absorb tremendous impact without

cracking or breaking. It is inherently flame retardantand offers exceptional resistance to bases and otherchemicals. The structure of PPSU is shown inFig. 11.13.

Its properties are summarized as follows:

� High deflection temperatures;

� Steam sterilizable with high retention of impactproperties;

� Inherently flame retardant;

Table 11.3 Material Properties Retained and Surface Erosion after Atlas Weather-Ometer� AcceleratedWeathering of Chevron Phillips Ryton� R4 Polyphenylene Sulfide4

Exposure Time(Days)

83.3 250 333 417 83.3 250 333


Tensile Strength 91.3 922 86.1 63.5 992 992 96.7

Elongation 109.1 125.5 111.8 54.5 87.5 77.5 792


Surface Erosion (mm) 0.33 0.51

Note: (1) Composition-carbon black 2%, glass fiber reinforcement 40%.

Table 11.4 Change in the Mechanical Properties of Fortron� PPS after UV Exposure in an Atlas Weather-Ometer�2

FortronGrade

ExposureTime [h]

TensileStrength[MPa]

Strain atBreak [%]

TensileModulus[MPa]

Notched ImpactStrength (Izod) [J/m]

1140L4Natural

0 181 1.7 15,200 85

200 181 1.7 15,200 85

500 179 1.6 15,200 85

1000 177 1.7 14,500 85

2000 176 1.6 14,500 85

1140L4Black

0 176 1.7 13,800 80

200 176 1.7 14,500 75

500 178 1.6 15,200 80

1000 176 1.7 14,500 80

2000 175 1.6 15,200 80

Note: Tensile test according to ASTM D 638 ASTM D 256. The tests used injection molded specimens according to ASTMG 23, Method 3, without water spray. It also involved a black standard temperature of 60 �C and a radiation intensity of0.35 W/m2$nm at a 30% relative humidity under a xenon arc lamp according to ASTM G 26. Mechanical properties weretested according to ASTM standards. None of the test specimen showed signs of erosion.


� Excellent thermal stability making films suitable;

� For applications where very low shrink at hightemperatures is needed; and

� Good electrical properties.

Manufacturers and trade names:Ajedium Films(a division of Solvay Solexis), Solvay AdvancedPlastics Radel� R; Evonik Industries Europlex�.

Applications and uses: Electrical/electronic,aircraft interiors and automotive industry.Data for PPSU plastics are found in Figs

11.14e11.16.

11.5 Polyethersulfone

PES is an amorphous polymer and a high-temperature engineering thermoplastic. Even thoughPES has high-temperature performance, it can beprocessed on conventional plastics processingequipment. Its chemical structure is shown inFig. 11.17. Its CAS number is 25608-63-3. PES has anoutstanding ability to withstand exposure to elevatedtemperatures in air and water for prolonged periods.

Figure 11.6 The effect of outdoorweathering exposure in Fuji City,Japan on the properties retentionof Ticona Fortron� 1140A1 blackPPS.2

Figure 11.7 The effect ofWeather-Ometer� exposure onthe properties retention of TiconaFortron� 1140A1 black PPS.2

Note: Light source: sunshinecarbon arc lamp, Black Paneltemperature 63 �C, Water spray12/60 min.

Figure 11.8 Structure of polysulfone (PSU).


Because PES is amorphous, mold shrinkage is lowand is suitable for applications requiring closetolerances and little dimensional change over a widetemperature range. Its properties include:

� Excellent thermal resistancedTg 224�C;

� Outstanding mechanical, electrical, flame andchemical resistance;

� Very good hydrolytic and sterilization resistance;and

� Good optical clarity.

Weathering Properties: The weatheringresistance of natural PES resin is not verygood and therefore it is not suitable for outdooruse.9

Table 11.5 Mechanical Properties Retained after Outdoor Weathering of Sabic Innovative Plastics LNP Glass-Reinforced Polysulfone in California and Pennsylvania5

Exposure Conditions





Notched Izod Impact Strength 100 90.9 100 90.9

Unnotched Izod Impact Strength 100 882 98 902

Note: (1) Carbon black 1%, glass fiber reinforcement 30%. (2) Exposure test method ASTM D1435.

Table 11.6 Effect of Benzotriazole Type UV Absorbers on the Yellowness Index of PSU Films6

UV Absorber Concentration

Yellowness Index after Exposure for hours

0 6 28 74 192

Without 3.7 7.7 13 21 33a

0.5% 3.8 6.4 10 16 26

1.0% 3.8 5.7 9.2 16 22

Note: (1) Exposure: Xenotest 1200 without water spraying, black panel temperature w53 �C. (2) Solution cast films0.1 mm thick. (3) Test method: ASTM 1925-70.aFilm is brittle.

Figure 11.9 Tensile strength afterxenon arc Weather-Ometer�

exposure of polysulfone.7


Figure 11.10 Delta E colorchange for natural resins 30 kJ/day xenon arc UV weathering ofPSU resin.8

Figure 11.11 Yellowness indexfor natural resins 30 kJ/day xenonarc UV weathering of PSU resin.8

Figure 11.12 Gloss (60�) fornatural resins 30 kJ/day xenon arcUV weathering of PSU resin.8


BASF Ultrason� moldings yellow and embrittledquickly when exposed outdoors. The moldings canbe protected from degradation by the incorporationof carbon black, surface coating or metallizing.10

Manufacturers and tradenames:BASFUltrason�

E, Sumitomo Chemical Co., Ltd. SUMIKAEXCEL�

PES, Solvay Advanced Polymers Veradel�.Data for PES plastics are found in Table 11.7 and

Figs 11.18e11.21.

11.6 Parylene (Poly(P-Xylylene))

Parylene is the generic name for members ofa series of polymers. The basic member of theseries, called Parylene N, is poly-para-xylylene,a completely linear, highly crystalline material. The

Figure 11.13 The structure of polyphenylsulfone(PPSU).

Figure 11.14 Delta E colorchange for natural resins 30 kJ/day xenon arc UV weathering ofPPSU resin.8

Figure 11.15 Yellowness indexfor natural resins 30 kJ/day xenonarc UV weathering of PPSU resin.8


structures of four Parylene types are shown inFig. 11.22.Parylene polymers are not manufactured and sold

directly. They are deposited from the vapor phase bya process which in some respects resembles vacuummetalizing. The Parylenes are formed at a pressure ofabout 0.1 torr from a reactive dimmer in the gaseousor vapor state. Unlike vacuum metalizing, the depo-sition is not line of sight, and all sides of an object tobe encapsulated are uniformly impinged by thegaseous monomer. Due to the uniqueness of the vaporphase deposition, the Parylene polymers can be

formed as structurally continuous films from as thin asa fraction of a micrometer to as thick as several mils.The first step is the vaporization of the solid dimer

at approximately 150 �C. The second step is thequantitative cleavage (pyrolysis) of the dimer vaporat the two methyleneemethylene bonds at about680 �C to yield the stable monomeric diradical, para-xylylene. Finally, the monomeric vapor enters theroom temperature deposition chamber where itspontaneously polymerizes on the substrate. Thesubstrate temperature never rises more than a fewdegrees above ambient.Parylene is used as a coating on medical devices

ranging from silicone tubes to advanced coronarystents, synthetic rubber products ranging frommedical grade silicone rubber to EPDM (ethylenepropylene diene monomer rubber).The manufacturer of coating equipment and

starting materials is Para Tech Coating, Inc. Theyalso offer coating services.

Figure 11.16 Gloss (60�) fornatural resins 30 kJ/day xenonarc UV weathering of PPSU resin.8

Figure 11.17 Structure of polyethersulfone (PES).

Table 11.7 Effect of Benzotriazole Type UV Absorbers on the Yellowness Index of PES Films6

UV Absorber Concentration

Yellowness Index after Exposure for Hours

0 6 28 74 192

Without 4.7 4.8 8.5 14a e

0.5% 5.5 4.2 6.1 11 16

1.0% 4.5 6.1 6.7 10 14

Note: (1) Exposure: Xenotest 1200 without water spraying, black panel temperature w53 �C. (2) Solution cast films0.1 mm thick. (3) Test method: ASTM 1925-70.aFilm is brittle.


Figure 11.18 Tensile strengthafter xenon arc Weather-Ometer�

exposure of PES.7

Figure 11.19 Delta E colorchange for natural resins 30 kJ/day xenon arc UV weathering ofPES Resin.8

Figure 11.20 Yellowness indexfor natural resins 30 kJ/day xenonarc UV weathering of PES resin.8


Weathering Resistance: Although stable indoors,the parylenes are not recommended for use outdoorswhen exposed to direct sunlight.11 Parylene filmswere exposed to radiation from a bank of fluorescentlamps with following details.12

� Device used: QUV�

� Test method: ASTM 154

� Type of test: Accelerated weathering

� Source: UVA 340 lamp

� Irradiance: 0.77 Watts per square meter

� Visual color, chalking, cracking, blistering andflaking were characterized on the films after 100,300, 500, 1000, 1250, 1500 and 2000 h of UVexposure. Numerical scales (0e10) are used to

Figure 11.21 Gloss (60�) fornatural resins 30 kJ/day xenon arcUV weathering of PES resin.8

Figure 11.22 Structures of the parylene polymer molecules.

Figure 11.23 Chemical structure of acetalhomopolymer. Figure 11.24 Chemical structure polyoxymethylene

copolymer monomers.

Figure 11.25 Chemical structureof acetal copolymer.


depict the degree of effect of the exposure. Theobservation results are summarized below (Scale:10dExcellent (no effect), 0dVery poor (verysevere)).

Results were:

� Parylene HT: Stability is more than 2000 hdAfter2000 h of exposure, there was no discoloration,chalking, cracking or blistering.

� Parylene C: Stability is less than 100 hdAfter100 h of exposure, film turned yellow (3Y), butthere was no chalking, cracking or blistering.

� Parylene N: Stability is less than 100 hdAfter100 h of exposure, film turned yellow (4Y), butthere was no chalking, cracking or blistering.

Manufacturers and trade names: Para TechCoating, Inc. Parylene.

11.7 Polyoxymethylene(POM or Acetal Homopolymer)/Polyoxymethylene Copolymer(POM-Co or Acetal Copolymer)

There are two variations to acetal plastics, homo-polymer and copolymer.

11.7.1 Polyoxymethylene(POM or Acetal Homopolymer)

Acetal polymers, also known as polyoxy-methylene (POM) or polyacetal, are formaldehyde-based thermoplastics that have been commerciallyavailable since the 1960s. Polyformaldehyde isthermally unstable. It decomposes on heating toyield formaldehyde gas. Two methods of stabilizingpolyformaldehyde for use as an engineering polymerwere developed and introduced by DuPont, in 1959,and Celanese in 1962 (now Ticona).

DuPont’s method for making polyacetal yieldsa homopolymer through the condensation reaction ofpolyformaldehyde and acetic acid (or acetic anhy-dride). The acetic acid puts acetate groups(CH3COOe) on the ends of the polymer as shown inFig. 11.23, which provide thermal protection againstdecomposition to formaldehyde.

Figure 11.26 Photolysis reactions of POM.

Figure 11.27 Acid-catalyzedhydrolysis POM.

Table 11.8 Weatherability of DuPont Delrin� 507 BK601 Acetal Homopolymer14

ExposureTime (Year)

Arizona Michigan

Tensile Strength (MPa) Elongation (%) Tensile Strength (MPa) Elongation (%)

0 70.3 20 70.3 20

1 71.0 12 70.3 7

2 71.7 11 70.3 13

3 71.0 9 70.3 12

4 73.1 11 72.4 14

10 69.6 10 69.6 10

20 70.2 8 64.4 11

Note: (1) Samples: ASTM tensile specimens, 216 mm� 13 mm� 3 mm (81/2 in.� 1/2 in.� 1/8 in.).


Further stabilization of acetal polymers alsoincludes the addition of antioxidants and acid scav-engers. Polyacetals are subject to oxidative andacidic degradation, which leads to molecular weightdecline. Once the chain of the homopolymer isruptured by such an attack, the exposed poly-formaldehyde ends may decompose to formaldehydeand acetic acid.

11.7.2 PolyoxymethyleneCopolymer (POM-Co or AcetalCopolymer)

The Celanese route for the production of polyacetalyields amore stable copolymer product via the reactionof trioxane, a cyclic trimer of formaldehyde, anda cyclic ether, such as ethylene oxide or 1,3 dioxolane.

Table 11.9 Color Differences, DE, after Light Exposure for Pigmented Ticona Celcon� UV90Z (GM and FordAutomotive Colors) Acetal, POM15

ColorGM Standard

BlackGM Garnet

RedGM Very Dark

SapphireGM MediumBeechwood

FordCorporate Red

ColorChange, DE

0.17 1.00 1.35 0.57 1.50

Note: (1) Exposure conditions SAE J1885, exposure energy 1240.8 kJ/m2, exposure time approx. 800 h.

Table 11.10 Color Differences, DE, after Light Exposure for Pigmented Ticona Celcon� UV90Z Acetal, POM15

Color BlackLightRed

LightTan

MediumTan Brown

MediumGray

DarkBlue

FlameRed Maroon

ColorChange, DE

0.2 0.2 0.2 0.6 0.2 0.3 0.5 0.9 1.2

Note: (1) Exposure conditions SAE J1885, exposure energy 1240.8 kJ/m2, exposure time approx. 800 h.

Table 11.11 Color Differences, DE, after Light Exposure for Unpigmented Ticona Celcon� M90UV Acetal,POM15

Exposure Conditions Initial Value HPUV Xenon Arc ASTM 4459

Exposure Time 300 HP units 200 h 600 h 1000 h

Color Change, Db 4.08 2.62 2.63 2.66 2.89

Note: (1) Initial b value 4.08; Db is a color value. (2) Lower values mean whiter samples.

Table 11.12 Color Differences, DE, after Florida Weathering for Ticona Hostaform� Acetal, POM MaterialGrade16

Ticona Hostaform� Product S 27072 WS 10/1570 C 9021 10/1570 C 9021 LS 10/1570

Color Change, DE 1.8 2.4 0.8

Note: (1) Exposure conditions Xenotest 1200 CPS (EDAG) VW PV 3920 (Florida), exposure time 1600 h.

Table 11.13 Color Differences, DE, after Xenotest 1200 for Ticona Hostaform� C 9021 LS Blue 80/4065 Acetal,POM17

Exposure Time 500 h 1000 h 1500 h 2000 h

Color Change, DE 1.2 1.3 1.6 2.2


The structures of these monomers are shown inFig. 11.24.Thepolymer structure is given inFig. 11.25.

The improved thermal and chemical stability ofthe copolymer versus the homopolymer is a result of

randomly distributed oxyethylene groups, which iscircled in Fig. 11.25. All polyacetals are subject tooxidative and acidic degradation, which leads tomolecular weight reduction. Degradation of thecopolymer ceases, however, when one of therandomly distributed oxyethylene linkages isreached. These groups offer stability to oxidative,thermal, acidic and alkaline attack. The raw copol-ymer is hydrolyzed to an oxyethylene end cap toprovide thermally stable polyacetal copolymer.

The copolymer is also more stable than thehomopolymer in an alkaline environment. Its oxy-ethylene end cap is stable in the presence of strongbases. The acetate end cap of the homopolymer,however, is readily hydrolyzed in the presence ofalkalis, causing significant polymer degradation.

Table 11.14 Changes in Mechanical Properties afterLight Exposure of Ticona Celcon� UV90Z15

Mechanical Property Property Retained

Tensile Strength 104.5%

Flexural Strength 100.8%

Flexural Modulus 96.7%

Notch Izod Impact 105.2%

Note: (1) Total light exposure energy 1240 kJ/m2

(approximately 800 h).

Figure 11.28 Relative tensilestrength after accelerated interiorweathering according to SAE J1885for DuPont Delrin� POM.14

Note: Improved weathering perfor-mance (retention of surface appear-ance as well as mechanicalproperties) is achieved in theDELRIN� x07 Series by the use ofa selected UV stabilizer package,as Fig. 11.28 illustrates.

Figure 11.29 Relative gloss afteraccelerated interior weatheringaccording to SAE J1885 forDuPont Delrin� POM.14

Note: Fig. 11.29 illustrates sche-matically how outstandingimprovements in weatherabilityhave been achieved through theselection and optimization of UVstabilizer systems for DELRIN�.


Figure 11.30 Retention of tensilestrength during natural exposurein Southern Slovakia.18

Figure 11.31 Elongation retentionduring POM natural exposure inrain tropics.19

Figure 11.32 Outdoor exposuretime vs. impact strength retainedof BASF Ultraform� N 2320 andUltraform� N 2325 U acetalcopolymer.20


Figure 11.33 Outdoor exposuretime vs. tensile impact strength ofTicona Celcon� M90 and UV90acetal copolymer.21

Figure 11.34 Outdoor exposuretime vs. tensile strength at yieldof Ticona Celcon� M90 acetalcopolymer.21

Figure 11.35 New Jerseyoutdoor exposure time vs. tensilestrength at yield of TiconaCelcon� GC25 a acetalcopolymer.21


Figure 11.36 QUV� exposuretime vs. DE color change of TiconaCelcon� acetal copolymer.21

Figure 11.37 Tensile strength vs.outdoor weathering of blackCelcon acetal copolymers.22

Note: Data for Celcon WR90Zgenerated using SAE test methodJ 1960; 2000 h exposure.

Figure 11.38 Change in color vs.simulated weathering time forCelcon UV90Z UV-stabilized acetalcopolymer (colored grades).22


Figure 11.40 Sunshine Weather-Ometer� exposure time vs. elon-gation retained of MitsubishiIupital� F20 acetal copolymer.23

Figure 11.41 Sunshine Weather-Ometer� exposure time vs. tensilestrength retained of MitsubishiIupital� F20 acetal copolymer.23

Figure 11.39 Change in color vs.simulated weathering time forCelcon M90� acetal copolymer(colored grades).22


Figure 11.42 Xenon arc Weather-Ometer� exposure time vs. rela-tive gloss of BASF Ultraform� Nacetal copolymer.24

Figure 11.43 Relative tensilestrength of unstabilized andUV-stabilized Hostaform C asa function of weathering time.25

Figure 11.44 Relative elongationat break of unstabilized andUV-stabilized Hostaform C asa function of weathering time.25


The homopolymer is more crystalline than thecopolymer. The homopolymer provides bettermechanical properties, except for elongation. Theoxyethylene groups of the copolymer provide

improved long-term chemical and environmentalstability. The copolymer’s chemical stability resultsin better retention of mechanical properties over anextended product life.

Acetal polymers have been particularly successfulin replacing cast and stamped metal parts due totheir toughness, abrasion resistance and ability towithstand prolonged stresses with minimal creep.Polyacetals are inherently self-lubricating. Theirlubricity allows the incorporation of polyacetal ina variety of metal-to-polymer and polymer-to-polymer interface applications such as bearings,gears and switch plungers. These properties havepermitted the material to meet a wide range ofmarket requirements.

Figure 11.45 Tensile strength (ISO1/4 tensile test bar) of HostaformC 9021, S 9064 and S 9244 inthe black 10/1570 formulation asa function of exposure time in theXenotest 1200.25

Figure 11.46 Elongation at break(ISO 1/4 tensile test bar) of Hosta-form C 9021, S 9064 and S 9244in the black 10/1570 formulationas a function of exposure time inthe Xenotest 1200.25

Figure 11.47 Chemical structure of polyphenyleneether/polyphenylene oxides (PPE or PPO).


The properties of polyacetals can be summarizedas follows:

� Excellent wear resistance;

� Very good strength and stiffness;

� Good heat resistance;

� Excellent chemical resistance;

� Opaque;

� Moderate to high price; and

� Somewhat restricted processing.

Weathering: Upon exposure to light, polyacetalsthat are not UV-stabilized display loss of gloss,

a change in color, and in some cases,chalkingdthe formation of a white coating on thesurface. This degradation process is accompaniedby a decrease in strength. The wavelength of solarradiation that is harmful to polyacetals is in therange of 290e400 nm.13

Photolysis leads to formation of radicals that maylead to the formation of formaldehyde as shown inFig. 11.26. Thermal oxidation and photooxidationare both accelerated in the presence of water. Watercan readily cleave the polymer backbone by acid-catalyzed hydrolysis as shown in Fig. 11.27.Copolymerization increases the durability of POM

over that of homopolymerization.

Figure 11.48 Photolysis reactions of PPO polymers.

Figure 11.49 Reactions of PPO polymerhydroperoxides.

Figure 11.50 Direct scission by photolysis of PPO polymer.



� UVA: 2-(2H-benzotriazol-2-yl)-p-cresol; 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol;

� HAS: 1,3,5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl (1,2,6,6-pentam-ethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]

imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)- ;

� Phenolic antioxidant: ethylene-bis(oxyethy-lene)-bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate);

� Optical brightener: Fluorescent brightener 378(Clariant).

Table 11.15 Change in Yellowness Index and Percentage Gloss Retained after Outdoor Weathering Exposure inArizona, Florida, and New York for GE Plastics Noryl� SE100-8078 Flame-Retardant Modified PPO29

Exposure Location Arizona Florida Selkirk, New York

Exposure Time (Days) 365 730 1096 365 730 1096 365 730 1096


Flexural Modulus 115.9 111.4 116.5 115.3 111.4 115 112.9 109.9 113.8

Ultimate TensileStrength

91.3 87 85.5 87 85.5 84.1 89.9 88.4 85.5

Tensile Strength 0 Yield 88.1 89.6 91 86.6 88.1 89.6 85.1 86.6 86.6

Flexural Strength 106.1 106.1 105.3 99.1 100.9 107.9 101.8 982 101.8

Elongation 33.3 222 13.9 33.3 25 16.7 55.6 413 30.6


72.9 72.9 64.6 70.8 64.6 58.3 89.6 87.5 83.3


D Yellowness Index 31.7 30 37.9 28.2 31.1 31.7 26.3 30.8 39

Gloss Retained (%) 7.3 7.1 6.5 5.8 3.7 3.7 6 4.3 4.7

Figure 11.51 Change in color, E,after accelerated indoor UV expo-sure of modified PPO.30


Figure 11.52 Dart drop impactstrength after Arizona outdoorweathering exposure of modifiedPPO.31

Figure 11.53 Percentage elonga-tion after Arizona outdoor weath-ering exposure of modified PPO.31

Figure 11.54 Tensile strength afterArizona outdoor weathering expo-sure of modified PPO.31


Manufacturers and trade names: DuPont�Delrin�, Ticona Celcon�.

Applications and uses: Metal and glassreplacement.

Data for acetal plastics are found in Tables11.8e11.14 and Figs 11.28e11.48.

11.8 Polyphenylene Oxide

Polyphenylene (PPE) plastics are also referred toas polyphenylene oxide (PPO). The structure of thepolymer is shown in Fig. 11.47.

The PPE materials are always blended or alloyedwith other plastics, so they are called modified PPE

or PPO. PPE is compatible with polystyrene (PS) andis usually blended with high-impact PS over a widerange of ratios. Because both PPE and PS plasticsare hydrophobic, the alloys have very low waterabsorption rates and high dimensional stability. Theyexhibit excellent dielectric properties over a widerange of frequencies and temperatures. PPE/PSalloys are supplied in flame retardant, filled andreinforced, and structural foam molding grades. PPEcan also be alloyed with polyamide (nylon) plasticsto provide increased resistance to organic chemicalsand better high-temperature performance.

Weathering:Photolysis of PPOpolymers is given inFig. 11.48. Subsequent reactions of the radicals formedby photolysis are shown in Figs 11.49 and 11.50.26

Figure 11.55 Change in color, E,after Arizona outdoor weatheringexposure of modified PPO.31

Figure 11.56 Change in color, E,after Ohio outdoor weathering expo-sure of modified PPO.31


PPO blends have good weathering resistance whenadequately stabilized, but uncolored grades willyellow in UV light. Black grades have the best UVresistance.27

Noryl� resins should not degrade, decompose,chalk, craze or crack on exposure to outdoorweathering.28

Noryl� resins will28:

1. Lose some impact and elongation (20e40%)strength depending on grade;

2. Gain tensile and flexural strength (5e15%) onlong-term exposure;

3. Lose any surface gloss within a few monthsand become dull; and

4. Change to a shade of color that is more yellowor darker on exposure.

Only surface discoloration will occur. However,very thin sections (under 12.7 mm) may becomemore brittle. This brittleness occurs because thesurface layers that are losing impact strengthand becoming stiffer make up a proportionatelylarger volume of a thin section than a thickersection.29

When exposed to outdoor light, parts of Noryl�

resin undergo a color change with a tendency todarken slightly and drift toward yellow. Whenselecting Noryl� resins for outdoor use, darkcolorsdblack and browndare recommended, aswell as reds, yellows and oranges, which showexcellent color stability and where the tendency toyellow is masked.

Products of photodegradation include hydroper-oxides, phenyl radicals, phenoxy radicals, benzylradicals and hydroxyl groups. Typical results ofphotodegradation include gel formation, yellowing,loss of mechanical properties, and decrease inmolecular weight.Stabilization: Most important stabilizers:

� UVA: 2,2’-methylenebis(6-(2H-benzotriazol-2-yl)-4-1,1,3,3-tetramethylbutyl) phenol;

� HAS: 1,3,5-triazine-2,4,6-triamine, N,N000[1,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pentam-ethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)- ; and

� Electron transfer quencher: 1,2,4-trimethoxy-benzene.

End-uses include automotive electrical applica-tions, water pump impellers, HVAC equipment,solar heating systems, packaging and circuitbreakers.Data for PPO plastics is shown in Table 11.15 and

Figs 11.51e11.57.

References

1. Victrex PEEK, supplier design guide (VK2/0586).ICI Advanced Materials; 1986.

2. Fortron� design technology. Polyplastics Co.;2012.

3. Das PK, DesLauriers PJ, Fahey DR, Wood FK,Cornforth FJ. Polym Deg Stab 1995;48:11.

Figure 11.57 Dart drop impactstrength after Ohio outdoor weath-ering exposure of modified PPO.31


4. Ryton polyphenylene sulfide compounds engi-neering properties, supplier design guide(TSM-266). Phillips Chemical Company; 1983.

5. Cloud P, Theberge J. Glass-reinforced thermo-plastics, thermal and environmental resistance ofglass reinforced thermoplastics, supplier tech-nical report. LNP Corporation; 1982.

6. Schmitter A. Ciba Specialty Chemicals; unpub-lished results.

7. Ultem design guide, supplier design guide(ULT-201G (6/90)RTB). General Electric Com-pany; 1990.

8. SABICdIp technical report 03-MTV-06weathering of polysulfones. Sabic InnovativePolymers; 2011.

9. Polyethersulfone (PES) technical literature.Mitsui Chemicals; 2005.

10. Ultrason E, Ultrason S. Product line, properties,processing, supplier design guide (B 602e/10.92). BASF Aktiengesellschaft; 1992.

11. http://www.paryleneengineering.com/optical_properties.html.

12. Rakesh Kumar. Parylene technology foradvanced packaging, protection & reliability ofelectronics. SCS; 2008.

13. Hostaform Report 118. Ticona; 2005.14. Delrin design guidedModule III. DuPont

Engineering Polymers; 1997.15. Celcon� acetal copolymer ultraviolet resistant

grades. Ticona; 2009.16. Inform automotive. Ticona; 2005.17. Hostaform report 118. Ticona; 2005.18. Vesely R, Kalenda M. Kunststoffe 1969;59:

107.

19. Taylor M. Joint tropical trials. Queensland,Australia.

20. Ultraform outdoor exposuredUnpublisheddata, supplier technical report. BASF; 1993.

21. Celcon acetal copolymer, supplier design guide(90e350 7.5M/490). Hoechst Celanese Corpo-ration; 1990.

22. Designing with Celcon�. Ticona; 2002.23. Engineering plastics acetal copolymerdIupital,

supplier design guide (M.G.C.91042000P.A.).Mitsubishi Gas Chemical Company, Inc.; 1991.

24. Topics in chemistrydBASF plastics researchand development, supplier technical report.BASF Aktiengesellschaft; 1992.

25. Hostaform� Polyoxymethylene Copolymer(POM). 2006.

26. Wypych G. Handbook of materials weathering.4th ed. Toronto: ChemTec Publishing; 2008.

27. Polymer data file: Polyphenylene oxide (mod-ified)dPPO (Noryl). Tangram Technology Ltd;2001.

28. Terluran product line, properties, processing,supplier design guide (B 567e/(8109) 9.90).BASF Aktiengesellschaft; 1990.

29. Weatherability of Noryl resins, supplier tech-nical report. General Electric Company; 1992.

30. Introducing superior UV stability with goodlooks that last in business machine housings,supplier marketing literature (7110). MonsantoChemical Company; 1990.

31. Engineering design guide to rigid Geon custominjection molding vinyl compounds, supplierdesign guide (CIM-020). BF Goodrich GeonVinyl Division; 1989.


http://www.paryleneengineering.com/optical_properties.html

http://www.paryleneengineering.com/optical_properties.html

12 Elastomers and Rubbers

12.1 Elastomers and Rubbers

An elastomer is a polymer with the property of“elasticity”, generally having notably low Young’smodulus and high yield strain compared with othermaterials.1 The term is often used interchangeablywith the term rubber. Elastomers are amorphouspolymers existing above their glass transition tem-perature so that considerable segmental motion ispossible, so it is expected that they would also be verypermeable. At ambient temperatures, rubbers are thusrelatively soft and deformable. Their primary uses arefor seals, adhesives and molded flexible parts. Elas-tomers may be thermosets (requiring vulcanization,a form of cross-linking) or thermoplastic, calledthermoplastic elastomer (TPE).

TPEs have two big advantages over the conven-tional thermoset (vulcanized) elastomers. Thoseare ease and speed of processing. Other advantagesof TPEs are recyclability of scrap, lower energycosts for processing, and the availability of stan-dard, uniform grades (not generally available inthermosets).

TPEs are molded or extruded on standard plastics-processing equipment in considerably shorter cycletimes than those required for compression or transfermolding of conventional rubbers. They are made bycopolymerizing two or more monomers, using eitherblock or graft polymerization techniques. One of themonomers provides the hard, or crystalline, polymersegment that functions as a thermally stablecomponent; the other monomer develops the soft oramorphous segment, which contributes the elasto-meric or rubbery characteristic.

Physical and chemical properties can becontrolled by varying the ratio of the monomersand the length of the hard and soft segments. Blocktechniques create long-chain molecules that havevarious or alternating hard and soft segments. Graftpolymerization methods involve attaching onepolymer chain to another as a branch. The prop-erties that are affected by each phase can begeneralized:

“Hard-Phase” - Plastic properties:

� Processing temperatures

� Continuous use temperature

� Tensile strength

� Tear strength

� Chemical and fluid resistance

� Adhesion to inks, adhesives and over-moldingsubstrates

“Soft-Phase” - Elastomeric properties:

� Lower service temperature limits

� Hardness

� Flexibility

� Compression set and tensile set

12.2 Thermoplastic PolyurethaneElastomers

Urethanes are a reaction product of a diisocyanateand long- and short-chain polyether, polyester, orcaprolactone glycols.2 The polyols and the short-chain diols react with the diisocyanates to form linearpolyurethane molecules. This combination of diiso-cyanate and short-chain diol produces the rigid orhard segment. The polyols form the flexible or softsegment of the final molecule. Figure 12.1 shows themolecular structure in schematic form.

There are three main chemical classes ofthermoplastic polyurethane elastomers (TPU):polyester, polyether and a smaller class known aspolycaprolactone.3

� Polyester TPUs are compatible with PVC andother polar plastics. Offering value in the formof enhanced properties they are unaffected byoils and chemicals, provide excellent abrasionresistance, offer a good balance of physical prop-erties and are perfect for use in polyblends.




� Polyether TPUs are slightly lower in specificgravity than polyester and polycaprolactonegrades. They offer low-temperature flexibilityand good abrasion and tear resilience. They arealso durable against microbial attack and provideexcellent hydrolysis resistancedmaking themsuitable for applications where water isa consideration.

� Polycaprolactone TPUs have the inherent tough-ness and resistance of polyester-based TPUscombined with low-temperature performance anda relatively high resistance to hydrolysis. Theyare an ideal raw material for hydraulic and pneu-matic seals.

TPUs can also be subdivided into aromatic andaliphatic varieties:

� Aromatic TPUs based on isocyanates like4,40-methylenediphenyl diisocyanate (MDI) areworkhorse products and can be used in applicationsthat require flexibility, strength and toughness.

� Aliphatic TPUs based on isocyanates likemethyldicyclohexyl-diisocyanate (H12 MDI),1,6-hexamethylene-diisocyanate and isophoronediisocyanate are light stable and offer excellentoptical clarity. They are commonly employed inautomotive interior and exterior applications andas laminating films to bond glass and polycarbonatetogether in the glazing industry. They are also usedin projectswhere attributes like optical clarity, adhe-sion and surface protection are required.

The properties of the resin depend on the nature ofthe raw materials, the reaction conditions and the

ratio of the starting raw materials. The polyols usedhave a significant influence on certain properties ofthe thermoplastic polyurethane. Polyether and poly-ester polyols are both used to produce manyproducts.The polyester-based TPUs have the following

characteristic features:

� Good oil/solvent resistance;

� Good UV resistance;

� Abrasion resistance;

� Good heat resistance; and

� Mechanical properties.

The polyether-based TPUs have the followingcharacteristic features:

� Fungus resistance;

� Low-temperature flexibility;

� Excellent hydrolytic stability; and

� Acid/base resistance.

In addition to the basic components describedabove, most resin formulations contain additives tofacilitate production and processability. Other addi-tives can also be included such as:

� Demolding agents;

� Flame retardants;

� Heat/UV stabilizers; and

� Plasticizers.

Figure 12.1 Molecular structure of a thermoplastic polyurethane elastomer.


The polyether types are slightly more expensiveand have better hydrolytic stability and low-temperature flexibility than the polyester types.

12.2.1 UV Radiation Resistance

Aromatic TPUs can yellow with exposure toUV radiation. In applications where a TPU willbe exposed to sunlight, the best course of action isto employ an aliphatic TPU, which will not yellowor degrade to the same extent with outdoorexposure.

Manufacturers and trade names: LubrizolEstane� TPU, Bayer MaterialScience Texin andDesmopan, BASF Elastollan�.

Data for TPU elastomers may be found in Tables12.1e12.4 and Figs 12.2e12.6.

12.3 Olefinic ThermoplasticElastomers

Polyolefin thermoplastic elastomer (TPO) materialsare defined as compounds (mixtures) of various

Table 12.1 Properties after Accelerated QUV� Weathering of Huntsman Krystalflex PE399, a High-PerformanceAliphatic Polyether TPU Film3

Properties

Exposure Hours

0 500 1000 1500 2000

Tensile Strength at Break, psi 4000 4000 3900 3500 4300

100% Tensile Modulus, psi 400 380 440 420 370

300% Tensile Modulus, psi 3500 2800 2500 2400 2000

Ultimate Elongation % 300 300 280 280 360

Tear Resistance, pli 140 125 125 125 170

Yellowness Index 042 1.73 2.08 1.86 2.52

Note: (1) Extruded film thickness: 25� 5mils. (2) Test methods: ASTM G53; D412; D-624. (3) Light source: UVA 340bulb, cycle: 4 h UV light at 60 �C, 4 h condensation at 45 �C, specimen preparation: without glass.

Table 12.2 Properties Retained after Fade-Ometer�-Accelerated Weathering for Noveon Estane� 58202 andEstane� 58300 TPU Elastomer4

Material Grade Estane 58202 Nat 023 Estane 58300 Nat 021

Features Natural Resin, Flame Retardant Natural Resin, Extrusion Grade


Shore A Hardness 82 82 82 82 80 80 80 80

Exposure Conditions

Exposure Time (Days) 0.83 2.5 42 8.3 0.83 2.5 4.2 8.3


100% Modulus 100 100 88.9 88.9 100 107.1 100 114.3

300% Modulus 109.1 104.5 100 100 97.6 107.3 102.4 97.6

Tensile Strength 92.8 89.2 84.3 77.1 101.1 101.1 84.3 77.5

Ultimate Elongation 101.6 101.6 104.8 100 97.2 95.8 95.8 100

Note: (1) Exposure test method: ASTM D1499.

12: ELASTOMERS AND RUBBERS 301

polyolefin polymers, semicrystalline thermoplasticsand amorphous elastomers. Most TPOs are composedof polypropylene and a copolymer of ethylene andpropylene called ethyleneepropylene rubber (EPM).7

A common rubber of this type is called EPDM rubber,which has a small amount of a third monomer, a diene

(two carbonecarbon double bonds in it). The dienemonomer leaves a small amount of unsaturation in thepolymer chain that can be used for sulfur cross-linking.Like most TPEs, TPO products are composed ofhard and soft segments. TPO compounds includefillers, reinforcements, lubricants, heat stabilizers,

Table 12.3 Properties Retained after Fade-Ometer� and QUV�-Accelerated Weathering for Noveon Estane�

58,315 Natural TPU Elastomer4

Exposure Conditions

Exposure Apparatus Fade-Ometer� QUV�

Exposure Time(Days)

2.5 42 8.3 12.5 8.3 20.8


100% Modulus 90.9 106.1 105.1 104.5 104 105

300% Modulus 95.4 105.1 99.7 100 98.3 94.9

Tensile Strength 100.9 104.9 99.9 91.7 81.6 71

Ultimate Elongation 101.8 101.8 104.4 100 102.6 101.8

Note: (1) Exposure test method: ASTM D149. (2) Shore A hardness: 85.

Table 12.4 Properties Retained after Fade-Ometer�-Accelerated Weathering for Noveon Estane� 58,315 andEstane� 58,863 Natural TPU Elastomer4

Material Grade Estane 58315 Estane 58863 Nat 025


Sample Thickness (mm) 0.38 0.38 0.38

Sample Length (mm) 152 152 152

Sample Width (mm) 12.7 12.7 12.7

Shore A Hardness (Units) 85 85 85 85 85 85 85

Exposure Conditions

Exposure Time (Days) 4.2 8.3 12.5 0.83 2.5 4.2 8.3


100% Modulus 107.2a 115.7a 125.3a 105 110 100 105

300% Modulus 102.8a 105.6a 102.1a 103.2 106.5 106.5 106.5

Tensile Strength 92.3a 96.4a 262a 109.1 107.3 100 74.5

Ultimate Elongation 103.6a 101.8a 55.4a 203.2 206.4 213 190.4

Photovolt Reflectance 100 100 91.3

Note: (1) Exposure test method: ASTM D149. (2) Shore A hardness: 85.aTest method: ASTMD882; strain rate: 508 mm/min; test note: jawspace is 50.8 mm, benchmark is 25.4 mm; test direction:transverse.


Figure 12.2 Elongation afterQUV� exposure of Dow Pellet-hane� 2103-80 AEF TPUelastomer.5

Figure 12.3 Tensile strengthafter QUV� exposure of DowPellethane� 2103-80 AEFTPU elastomer.5

Figure 12.4 Yellowness indexafter QUV� exposure of Dow Pel-lethane� 2103-80 AEF TPUelastomer.5


antioxidants, UV stabilizers, colorants and processingaids. They are characterized by high impact strength,lowdensity andgoodchemical resistance; theyareusedwhen durability and reliability are primary concerns.Manufacturers and trade names: Advanced

Elastomer Systems Santoprene�, LyondellBasellAdvanced Polyolefins Dexflex�.

Applications and uses: Roofing and automo-tive exterior parts, capping distilled water, dairyproducts, fruit juices, sports drinks, beer, wine,and food, cosmetics, toiletries, and pharma-ceutical packaging, sterilized closures, seals andliners.Data for TPO are found in Tables 12.5e12.15.

Figure 12.5 Yellowness indexafter QUV� exposure of BASFElastollan� 1185A-10 TPUelastomer.6

Figure 12.6 Tensile strengthafter xenon Weather-Ometer�

exposure of BASF Elastollan�

1185A-10 TPU elastomer.6


Table 12.5 Retention of Mechanical Properties after Xenon Arc Exposure for Black UV Grades of AdvancedElastomer Systems Santoprene� TPV Olefinic Thermoplastic Elastomer1

Grades 121-67 121-73 121-80

Shore A Hardness 67 73 80

Shore D Hardness

Exposure Time (h) 3000 5000 3000 5000 3000 5000


Tensile Strength 91 83 78 73 81 74

Elongation 98 93 75 72 78 74

100% Modulus 107 110 105 102 102 97

Grades 121-87 123-40 123-50


Shore A Hardness 87

Shore D Hardness 40 50

Exposure Time (h) 3000 5000 3000 5000 3000 5000


Tensile Strength 88 87 94 96 92 95

Elongation 89 84 92 89 93 91

100% Modulus 99 104 99 109 105 107

Note: (1) Xenon arc exposure, SAE J1885.

Table 12.6 Material Properties after Arizona Outdoor Exposure for Black UV Grades of Advanced ElastomerSystems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-67 121-73 121-80 121-40 101-64 103-40

Shore A Hardness 67 73 80 40 64

Shore D Hardness 40

Color Change (DE)

6 Months 3.6 4.6 1.6 0.3 5.2 3

12 Months 2.9 3.3 1.1 1.4 3.1 7.3

24 Months 1.4 2 1.4 2.7 1.7 8.3

48 Months 1.2 1.6 1.7 2.8 1.5 11.9

Change in Hardness

Shore A (6 Months) �1 2 3 2

Shore D (6 Months) 5 4

(Continued )


Table 12.6 (Continued)

Grades 121-67 121-73 121-80 121-40 101-64 103-40



Shore A (24 Months) �1 �1 4 3


Shore A (48 Months) 1 4 6 3


Tensile Strength Retained (%)

6 Months 88 85 80 97 75 95

12 Months 83 78 77 94 74 98

24 Months 87 79 76 99 75 92

48 Months 76 77 63 97 75 96

Elongation Retained (%)

6 Months 83 84 80 94 69 95

12 Months 84 81 79 92 72 95

24 Months 86 80 75 98 74 91

48 Months 93 83 77 94 73 94

Note: (1) Arizona outdoor exposure, SAE J1545. (2) Hardness test method ASTM D2240. (3) Tensile strength test methodASTM D412. (4) Elongation test method ASTM D412.

Table 12.7 Material Properties after Arizona Outdoor Exposure with Spray for Black UV Grades of AdvancedElastomer Systems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-67 121-73 121-80 121-40 101-64 103-40

Shore A Hardness 67 73 80 40 64

Shore D Hardness 40

Color Change (DE)

6 Months �1 4 3 5 1 3

12 Months �1 �4 4 5 1 1

24 Months �1 2 5 6 2 2

48 Months 4 5 9 2 7

Change in Hardness







Table 12.7 (Continued )

Grades 121-67 121-73 121-80 121-40 101-64 103-40


Shore A (48 Months) 4 5 2



6 Months 83 58 76 96 74 92

12 Months 89 77 76 97 77 93

24 Months 90 82 79 101 70 97

48 Months 84 80 100 75 99


6 Months 77 75 79 87 72 93

12 Months 88 78 82 85 74 91

24 Months 89 82 83 96 73 97

48 Months 87 87 98 76 97

Note: (1) Arizona outdoor exposure with spray, SAE J1545. (2) Tensile strength test method ASTM D412. (3) Elongationtest method ASTM D412. (4) Hardness test method ASTM D2240.

Table 12.8 Material Properties after Florida Outdoor Exposure for Black UV Grades of Advanced ElastomerSystems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-67 121-73 121-80 123-40 101-64 103-40

Shore A Hardness 67 73 80 64


Color Change (DE)

6 Months 5.4 5.6 2.3 1.2 6.3 2.7

12 Months 4.8 5 2.1 0.9 4.4 9.1

24 Months 1.1 1.5 0.4 0.9 1.2 11.2

48 Months 1 1.3 2.4 3.2 1.7 11.7

Change in Hardness





Shore A (24 Months) 0 �3 5 2



(Continued )



Grades 121-67 121-73 121-80 123-40 101-64 103-40



6 Months 89 82 84 97 78 98

12 Months 93 85 81 97 80 97

24 Months 82 81 78 98 69 95

48 Months 93 88 87 96 73 98


6 Months 87 86 88 98 78 100

12 Months 92 87 83 99 80 96

24 Months 80 86 84 96 75 97

48 Months 96 93 92 94 78 99

Note: (1) Exposure conditions Florida outdoor exposure. (2) Tensile strength test method ASTM D412. (3) Elongation testmethod ASTM D412. (4) Hardness test method ASTM D2240.

Table 12.9 Material Properties after Florida Outdoor Exposure with Spray for Black UV Grades of AdvancedElastomer Systems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-67 121-73 121-80 123-40 101-64 103-40



Color Change (DE)

6 Months 3.2 3.9 1.4 1.5 6.6 4.8

24 Months 3 3.4 6.5 1.3 2.6 8.5

48 Months 1.8 1.6 2.1 2.6 1.43 16.2

Change in Hardness








6 Months 89 77 84 99 79 96

24 Months 85 81 80 101 71 97

48 Months 93 84 87 103 71 65



Grades 121-67 121-73 121-80 123-40 101-64 103-40


6 Months 90 80 89 99 83 98

24 Months 86 82 82 97 69 97

48 Months 93 86 90 100 75 48

Note: (1) Exposure conditions Florida outdoor exposure with spray. (2) Hardness test method ASTM D2240. (3) Tensilestrength test method ASTM D412. (4) Elongation test method ASTM D412.

Table 12.10 Material Properties after EMMA-Accelerated Exposure with Spray for Black UV Grades of AdvancedElastomer Systems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-73 123-40 101-73 103-40

Shore A Hardness 73 73


Color Change (DE)

6 Months 3.4 8.3 5.8 15

12 Months 2.3 8.9 5.5 14.6

24 Months 2.5 8.7 5.2 12.2

Change in Hardness

Shore A (6 Months) 2 8




Shore A (24 Months) �3 5



6 Months 82 94 82 86

12 Months 85 100 84 82

24 Months 95 101 85 58


6 Months 72 80 67 69

12 Months 81 79 67 65

24 Months 52 76 50 6

Note: (1) EMMA-accelerated exposure, SAE J1545. (2) Hardness test method ASTM D2240. (3) Tensile strength testmethod ASTM D412. (4) Elongation test method ASTM D412.


Table 12.11 Material Properties after EMMAQUA�-Accelerated Exposure for Black UV Grades of AdvancedElastomer Systems Santoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-73 123-40 101-73 103-40



Color Change (DE)

6 Months 3.6 9.5 6.8 15

12 Months 3 8.4 5.5 14.9

24 Months 2.1 7.3 5.2 9.5

Change in Hardness





Shore A (24 Months) �5 4

Shore D (24 Months) 0 �3


6 Months 88 98 87 88

12 Months 87 114 90 75

24 Months 55 31 57 11


6 Months 85 82 77 75

12 Months 66 73 62 61

24 Months 68 2 49 1

Note: (1) EMMAQUA�-accelerated exposure, SAE J1545. (2) Hardness test method ASTM D2240. (3) Tensile strengthtest method ASTM D412. (4) Elongation test method ASTM D412.

Table 12.12 Material Properties after Xenon Arc Exposure for Black UV Grades of Advanced Elastomer SystemsSantoprene� TPV Olefinic Thermoplastic Elastomer8

Grades 121-67 121-73 121-80 123-40 101-64 103-40



Color Change (DE)

3000 h 1.5 2 2.3 2.7 7.8 5.3

5000 h 2 2.1 6.5 2.1 2.5 9.5

Change in Hardness

Shore A (3000 h) 3 2 4 1

Shore D (3000 h) 5 3



Grades 121-67 121-73 121-80 123-40 101-64 103-40

Shore A (5000 h) 2 2 5 1

Shore D (5000 h) 7 3


3000 h 91 78 81 94 61 88

5000 h 83 73 74 96 64 84


3000 h 98 75 78 93 57 88

5000 h 93 72 74 90 67 84

Note: (1) Xenon arc exposure, SAE J1885. (2) Hardness test method ASTM D2240. (3) Tensile strength test method ASTMD412. (4) Elongation test method ASTM D412.

Table 12.13 Material Properties after Xenon Arc SAE J1960 Exterior Automotive Testing for AdvancedElastomer Systems Santoprene� TPV High-Flow Grades Olefinic Thermoplastic Elastomer8

Grades 121-50 M100 121-62 M100 121-75 M100

Shore A Hardness 50 62 75

Property/Exposure Energy

Color Change (DE)

600 kJ/m2 0.7 0.8 0.9

1240 kJ/m2 1.0 0.4 1.3

1800 kJ/m2 0.7 1.3 1.2

2500 kJ/m2 2.4 1.8 1.8

Change in Hardness (Shore A)

600 kJ/m2 2 3 4

1240 kJ/m2 3 4 5

1800 kJ/m2 2 5 4

2500 kJ/m2 2 4 5

Tensile Strength (%Loss)

600 kJ/m2 12 11 8

1240 kJ/m2 12 16 5

1800 kJ/m2 14 21 11

2500 kJ/m2 11 19 7

Elongation Change (%Loss)

600 kJ/m2 14 13 10

1240 kJ/m2 12 22 7

1800 kJ/m2 12 26 12

2500 kJ/m2 7 24 12

Note: (1) Exposure conditions SAE J1960 exterior automotive. (2) Hardness test method ASTMD2240. (3) Tensile strengthtest method ASTM D412. (4) Elongation test method ASTM D412. (5) Color test method SAE J1545.


Table 12.14 Material Properties after UV-CON-Accelerated Indoor Exposure of SO.F.TER. SPA Forprene� Olefinic Thermoplastic Elastomer2

Forprene�

Grade 630 631 632 633 634 635 636 637 638 639 640 641 642 643


Shore AHardness

55 60 65 70 75 80 85 90

Shore DHardness

40 45 50 55 60 65


TensileStrength

95 95 93 94 94 95 95 97 96 96 96 98 98 99

Elongation 94 93 93 93 92 92 93 93 95 96 96 97 97 98

Change in Physical Characteristics

Shore AHardnessChange

3 3 2 2 2 2 2 2

Shore DHardnessChange

1 1 1 0 0 0

Note: (1) Exposure apparatus UV-CON. (2) Exposure test method ASTM D4329. (3) UV cycle: 4 h on, 4 h off. (4) Condensation cycle: 4 h on, 4 h off. (5) Exposuretemperature 60 �C. (6) Exposure time 7 days.

Table 12.15 UV Resistance after Accelerated UV Light Exposure of SO.F.TER. SPA Forprene� Olefinic Thermoplastic Elastomer9

Forprene�

Grade 630 631 632 633 634 635 636 637 638 639 640 641 642 643


Shore AHardness

55 60 65 70 75 80 85 90

Shore DHardness

40 45 50 55 60 65

Results Of Exposure

UVresistance

Excellent Excellent

Note: (1) Exposure apparatus xenon lamp. (2) Exposure temperature 40 �C. (3) Exposure time 41.7 days.

312

THEEFFECT

OFUV

LIG

HT

ANDW

EATHER

ONPLASTIC

SANDELASTOMERS

12.4 Thermoplastic CopolyesterElastomers

Thermoplastic copolyester elastomers are blockcopolymers.10 The chemical structure of one suchelastomer is shown in Fig. 12.7.

These TPEs are generally tougher over a broadertemperature range than the urethanes described inSection 12.2. Also, they are easier and moreforgiving in processing.

� Excellent abrasion resistance

� High tensile, compressive and tear strength

Figure 12.7 Molecular structureof Ticona Riteflex� thermo-plastic copolyester elastomers.

Table 12.16 Material Properties Retained and Surface and Appearance after Florida Outdoor Weathering forDuPont Hytrel� Polyester Thermoplastic Elastomer11

Material Grade

DuPontHytrel

HT-X-3803

DuPontHytrel

HT-X-3803 DuPont Hytrel 4056DuPont Hytrel

4056


Shore D Hardness 63 63 63 63


Carbon Black (wt%) 0 0

SAF Black (MasterbatchForm) (wt%)

0.5 0.5 0.5 0.5 0.5 1 1 1

Exposure Conditions

Exposure Time (Days) 182 365 182 365 182 365 730 182 365 730


Tensile Strength 70 58 94 97 96 100 80 97 106 99

Elongation at Break 13 0.5 93 75 104 112 102 104 110 104


Surface Appearance Note Good for allblackspecimenswith loss ofgloss atextendedexposures,but nosurfacecrazing

Good for all blackspecimens with loss ofgloss at extendedexposures, but nosurface crazing

Good for all blackspecimens withloss of gloss atextendedexposures, but nosurface crazing

Note: (1) Sample thickness 1.9 mm, exposure 45� south.


� Good flexibility over a wide range of temperatures

� Good hydrolytic stability

� Resistance to solvents and fungus attack

� Selection of a wide range of hardness

In these polyester TPEs, the hard polyestersegments can crystallize, giving the polymer some ofthe attributes of semicrystalline thermoplastics, mostparticularly better solvent resistance than ordinaryrubbers, but also better heat resistance. Above themelting temperature of the crystalline regions, theseTPEs can have low viscosity and can be moldedeasily in thin sections and complex structures.Properties of thermoplastic polyester elastomers canbe fine-tuned over a range by altering the ratio ofhard to soft segments.In DuPont Hytrel� polyester TPEs, the resin is

a block copolymer. The hard phase is polybutylene

terephthalate. The soft segments are long-chainpolyether glycols.Weathering Properties: For outdoor applications,

Hytrel� should be protected fromUVattack. Themostefficient method is the incorporation of low levels ofcarbon black. Where nonblack products are desired,weather protection is most efficiently obtained byincorporation of UV stabilizers alone (natural) or incombination with low levels of colored pigments.11

Manufacturers and trade names: TiconaRiteflex�, DuPont� Hytrel�, Eastman Ecdel�,DSM Engineering plastics Arnitel�.Data for thermoplastic polyester elastomers are

found in Tables 12.16e12.25.

12.5 Butyl Rubber

Butyl is an elastomeric copolymer of isobutylenewith small amounts of isoprene (1e2.5 mol %). Itsstructure is shown in Fig. 12.8.

Table 12.17 Material Properties Retained and Surface and Appearance after Florida Outdoor Weathering forDuPont Hytrel� 40D Polyester Thermoplastic Elastomer with Carbon Black3

MaterialGrade

Dupont Hytrel40D

Dupont Hytrel40D


SAF Black(MasterbatchForm, wt%)

0.5% 0.5% 0.5% 0.5% 1% 1% 1% 1%

Exposure Conditions

Exposure Time(Days)

182 365 730 1826 182 365 730 1826


TensileStrength

95.5a 100a 79.9a 60.4a 977a 107a 99a 68.2a

Elongation atBreak

104a 113a 102a 136a 104a 111a 104a 119a

Surface And Appearance

SurfaceAppearanceNote

Very good withloss of gloss butno surfacecrazing

Very goodwith loss ofgloss but nosurfacecrazing

Note: (1) Sample thickness 1.9 mm. (2) Shore D hardness 40. (3) Exposure 45� south.aStrain rate: 50.8 mm/min.


Table 12.18 Material Properties Retained after Delaware Outdoor Weathering for DuPont Hytrel� 5556 Polyester Thermoplastic Elastomer with CarbonBlack12


SAF (N110) Black (MasterbatchForm, 0.018e0.020 microns, wt%)

0.5 0.5 0.5 0.94 0.94 1.5 1.5 3 3 3

Exposure Conditions

Exposure Time (Days) 182 730 1278 182 730 182 730 182 730 1278


Tensile Strength 42.3 Too brittle totest

Too brittle totest

67.4 18.4 73 33 83.3 45.6 40.6

Elongation at Break 52.1 Too brittle totest

Too brittle totest

80.6 3.5 86.5 49 87.7 61.6 54.8

Note: (1) Compression molded film. (2) Sample thickness 0.25 mm.

Table 12.19 Material Properties Retained and Surface and Appearance after Florida Outdoor Weathering for Varying Thicknesses of DuPont Hytrel�

6345 Polyester Thermoplastic Elastomer Films with Carbon Black11


Sample Thickness (mm) 0.15 0.13 0.13 0.13 0.13 0.19 0.19 0.19 0.19 0.25 0.25 0.25 0.25


Carbon Black (MasterbatchForm, wt%)

0.80 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9

Exposure Conditions

Exposure Time (Days) 182 182 365 730 1096 182 365 730 1096 182 365 730 1096


Tensile Strength 21 53 71 39 34 56 64 51 36 72 73 67 62

Elongation at Break 6.2 108 104 40 26 96 100 56 36 91 100 91 87

Surface And Appearance

Surface Appearance Note Good for all black specimens with loss of gloss at extended exposures, but no surface crazing

Note: (1) Extruded film, black color. (2) Shore hardness 63. (3) Hytrel 10MS (polycarbodiimide moisture stabilizer, 1.9 wt%).

12:ELASTOMERS

ANDRUBBERS

315

Table 12.20 Material Properties Retained after Carbon Arc-Accelerated Weathering for DuPont Hytrel� 40DPolyester Thermoplastic Elastomer12


SAF Black (Masterbatch Form, wt%) 0.5 0.5 1 1

Exposure Conditions



Tensile Strength 97.8a 84.3a 104a 104a

Elongation at Break 113a 109a 111a 106a

Note: (1) Product form injection molded slab. (2) Shore D hardness 40. (3) Sample thickness 1.9 mm.aStrain rate: 50.8 mm/min.

Table 12.21 Material Properties Retained after Carbon Arc-Accelerated Weathering for DuPont Hytrel� 5556Polyester Thermoplastic Elastomer with Varying Levels of Carbon Black12


SAF (N110) Black (Masterbatchform,0.018e0.020 microns,wt%)

0.5 0.5 0.94 0.94 1.5 1.5 1.5 3 3 3

Exposure Conditions

Exposure Time (Days) 42 10.9 4.2 10.9 42 12.5 25 4.2 12.5 25


Tensile Strength 35 26 69.5 28.5 66.4 38 27 82.8 65.7 46

Elongation at Break 42.5 14.5 90.3 18.1 97 54 5.4 94.5 822 63

Note: (1) Compression molding film. (2) Sample thickness 0.25 mm.

Table 12.22 Material Properties Retained and Surface and Appearance after Carbon Arc-AcceleratedWeatheringfor DuPont Hytrel HT-X-3803 and 4056 Polyester Thermoplastic Elastomers with Varying Levels of Carbon Black11

Material GradeHytrel�

HT-X-3803 Hytrel HT-X-3803 Hytrel 4056 Hytrel 4056


Carbon Black (wt%) 0% 0%

SAF Black (MasterbatchForm, wt%)

0.5 0.5 0.5 0.5 0.5 0.5 1 1

Exposure Conditions

Exposure Time (Days) 20.8 41.7 20.8 41.7 83.3 166.7 20.8 41.7 20.8 41.7


Tensile Strength 73 30 96 99 100 86 se 84 104 103

Elongation at Break 2.6 2.6 88 81 93 96 112 108 110 106


Surface AppearanceNote

Good for all black specimenswith loss of gloss at extendedexposures, but no surfacecrazing

Good for all black specimenswith loss of gloss at extendedexposures, but no surfacecrazing

Note: (1) Injection-molded slab. (2) Shore D hardness 63. (3) Sample thickness 1.9 mm.


Table 12.23 Hytrel� 20UV Extends Serviceability of Hytrel� During Weather-Ometer� Exposure13

Composition (Parts)

Parts Hytrel� 5556 100 100 100

Parts Hytrel� 20UV e 2.5 4

Letdown Ratioa e 40:1 25:1

Originalb

Tensile Strength at Break, MPac 50.8 53.4 41.6

Elongation at Breakc, % 720 750 730

Exposure Time, h 48 300 300

Tensile Strength at Break, MPa 16.8 19.8

Elongation at Break, % 410 460

Exposure Time, h e 658 1000

Tensile Strength at Break, MPa e 11.2 10.8

Elongation at Break, % e 30 50aPellets dried, extrusion blended, pelletized and dried again.bCompression molded film, 0.275 mm (0.011 in.) thick.cTensileand elongation measurements were carried out using a head speed of 50 mm/min (2 in./min).

Table 12.24 Effect of Level of Carbon Black on 2.5 mm Films of Hytrel� 5556 after Weatheringa 13

Hytrel� 5556

Composition

Hytrel� 5556:Hytrel� 40CB e 16:1 7:1

Total Carbon Black, % 0 1.47 3.13

Originalb

Tensile Strength at Break, MPa 31.4 36.4 38.8

Elongation at Break, % 430 535 535

Exposure Time, h 50 50 50



Exposure Time, h 150 150








Elongation at Break, % 130 235aPellets of Hytrel� 40CB and Hytrel� 5556 were tumble blended and extruder melt blended prior to film preparation; filmwas made by compression molding; Weather-Ometer� carbon arc.bProperties determined at a crosshead speed of 50.8 mm/min (2 in./min).


Manufacturers and trade names: Lanxess Butyl,ExxonMobil Chemical, (Polysar is obsolete).Applications and uses: major application area is

the tire industry, mainly used for inner tubes andtire-curing bladders. Nontire applications include

pharmaceutical closures, roof membranes, bodymounts and tank linings.Data for butyl rubber are shown in Figs

12.9e12.13.

Table 12.25 Effect of Level of Carbon Black on 2.5 mm Films of Hytrel� Exposed in Floridaa13

Hytrel� 5556

Composition

(Hytrel� 5556/Hytrel� 40CB) d 16:1 7:1

Total Carbon Black, % 0 1.47 3.13

Originalb

Tensile Strength at Break,MPa

31.4 36.4 38.8

Elongation at Break, % 430 535 535

Exposure Time, Month 3 3 3


26.0 30.4


Exposure Time, Month 6 6


21.6 25.2


Exposure Time, Month 9 9


19.4 23.0

Elongation at Break, % 380 455aPellets of Hytrel� 40CB and Hytrel� 5556 were tumble blended and extruder melt blended priorto film preparation; film was made by compression molding; outdoor aging in Florida, 5� south.bProperties determined at a crosshead speed of 50.8 mm/min (2 in./min).

Figure 12.8 Chemical structure of butyl rubber.


Figure 12.9 Micro-IRHD hardnesschange vs. QUV� exposure of twoLanxess butyl rubber compounds.2

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps with a blackpanel temperature of 45 �C anda cycle of 4 h condensation and4 h drying (3 cycles per day).

Figure 12.10 Tensile strengthchange vs. QUV� exposure oftwo Lanxess butyl rubbercompounds.2

Note: Test pieces wereexposed in QUV� fluorescenttube apparatus using UVA340A lamps with a black paneltemperature of 45 �C anda cycle of 4 h condensationand 4 h drying (3 cycles perday).

Figure 12.11 Modulus at 100%vs. QUV� exposure of two Lanx-ess butyl rubber compounds.2

Note: Test pieces were exposedin QUV� fluorescent tube appa-ratus using UVA 340A lampswith a black panel temperatureof 45 �C and a cycle of 4 hcondensation and 4 h drying (3cycles per day).


12.6 Chlorobutyl Rubber(Polychloroprene)

Chlorobutyl rubber or polychloroprene is elasto-meric isobutyleneeisoprene copolymer (haloge-nated butyl) containing reactive chlorine.

Polychloroprene was developed in 1930 byDupont� and is best known under the nameneoprene. The polymer is made from chloropreneand its structure is given in Fig. 12.14. Its CASnumber is 9010-98-4. The polymer is often modifiedto permit some degree of polymerization. Sulfur is

Figure 12.12 Modulus at 300%vs. QUV� exposure of two Lanx-ess butyl rubber compounds.2

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps witha black panel temperature of45 �C and a cycle of 4 h conden-sation and 4 h drying (3 cyclesper day).

Figure 12.13 Elongation atbreak vs. QUV� exposure oftwo Lanxess butyl rubbercompounds.2


Figure 12.14 Polymerization of chloroprene.


a common modifier and the compounds are oftencalled vulcanizates.

DuPont Elastomer Neoprene is available in manyvarieties including nonsulfur-modified “W” and themore common sulfur-modified “GN” types. Poly-chloroprene is known for its resistance to oil, gaso-line, sunlight, ozone and oxidation though there are

other polymers that have better resistance to thesesame elements. Polychloroprene’s advantage is itsability to combine these properties moderately intoone all-purpose polymer.

Manufacturers and trade names: DuPont�Performance Elastomers Neoprene (discontinued),Exxon� Chlorobutyl, Lanxess Baypren�.

Table 12.26 Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering, AcceleratedOutdoor Weathering by EMMAQUA� and Xenon Arc-Accelerated Outdoor Weathering for Black DuPont Neo-prene� W Neoprene Rubber14

Exposure Conditions

Exposure Type Outdoorweathering

Accelerated outdoorweathering

Accelerated weathering

Exposure Location Arizona Arizona

Exposure Apparatus EMMAQUA Xenon arc Weather-Ometer�

Exposure Time(Days)

365 365 216

Exposure Note Water spray added


Tensile Strength 79.5 60.1 70.4

Elongation 77.9 28.2 15.3


DE Color Change 7.7 9.5 92.

Table 12.27 Material Properties Retained, Hardness Change, and Color Change after Arizona and FloridaOutdoor Weathering for Black DuPont Neoprene� W Neoprene Rubber15

Exposure Conditions

Exposure Location Arizona Arizona Arizona Arizona Florida



Tensile Strength 71a

Elongation 70a


Hardness Change (Units) 4b


DE Color Change (Samples Washed) 9.6 10.18 3.2 11.0

Note: (1) Black color, commercially available grade.aTest method: ASTM D412.bTest method: ASTM D2240.


Applications and uses: Chlorobutyl’s majorapplication area is the tire industry. It is mainly usedin tubeless tire inner liners, sidewalls and inner tubes.Other applications include conveyor belts requiringhigh-temperature resistance, tank linings for

chemical resistance and pharmaceutical closures andadhesives, gloves, adhesives, binders, coatings, dip-ped goods, elasticized asphalt and concrete.Data for polychloroprene rubber are found in

Tables 12.26 and 12.27 and Figs 12.15e12.19.

Figure 12.15 Micro-IRHD hardness change vs. QUV� exposure of several DuPont polychloroprenecompounds.16

Note: Test pieces were exposed in QUV� fluorescent tube apparatus using UVA 340A lamps with a black paneltemperature of 45 �C and a cycle of 4 h condensation and 4 h drying (3 cycles per day).

Figure 12.16 Tensile strength change vs. QUV� exposure of several DuPont polychloroprene compounds.16

Note: Test pieces were exposed in QUV� fluorescent tube apparatus using UVA 340A lamps with a black paneltemperature of 45 �C and a cycle of 4 h condensation and 4 h drying (3 cycles per day).


Figure 12.17 Elongation at breakvs. QUV� exposure of severalDuPont polychloroprenecompounds.16


Figure 12.18 Modulus at 100% vs.QUV� exposure of several DuPontpolychloroprene compounds.16

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps with a blackpanel temperature of 45 �C anda cycle of 4 h condensation and4 h drying (3 cycles per day).

Figure 12.19 Modulus at300% vs. QUV� exposure ofseveral DuPont polychloro-prene compounds.16

Note: Test pieces wereexposed in QUV� fluorescenttube apparatus using UVA340A lamps with a black paneltemperature of 45 �C anda cycle of 4 h condensationand 4 h drying (3 cycles perday).


12.7 EthyleneePropyleneRubbers (EPM, EPDM)

There are two basic types of ethyleneepropylenerubber available. ASTM classifies this syntheticelastomer as “EPM”, meaning that it has a saturatedpolymer chain of the polymethylene type. Within

this classification there are two basic kinds of eth-yleneepropylene rubber:

� EPM, the copolymer of ethylene and propylene.

� EPDM, the terpolymer of ethylene, propylene anda nonconjugated diene with residual unsaturationin the side chain.

Table 12.28 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weathering of White,Randomly Selected, Unstrained EPDM Terpolymer17

Exposure Conditions

Exposure Type Accelerated outdoor weathering Outdoor weathering

Exposure Location New River, Arizona Homestead, Florida

Exposure Apparatus EMMA, Fresnel concentrator with 10 mirrors

Exposure Note Water spray at night only; specimensmounted on kiln dried white oak boards;unstrained specimens

45� angle south; specimensmounted on kiln-dried white oak;unstrained specimens

Exposure Time (Days) 19 44 61 132 182 365 730

Total Irradiation (MJ/m2) 4000 8000 12,000 20,000 4290 6276 12,505

UV Irradiation (MJ/m2) 110 242 394 462 144 282 562


Tensile Strength 96.3 96.3 88.8 88.8 102 81.4 76.2

Elongation at Break 104 104 98 96 104 106 98

Note: (1) White color; randomly selected samples from different manufacturers.

Table 12.29 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weathering of Black,Weather Resistant, Unstrained EPDM Terpolymer17

Exposure Conditions




Exposure Note Water spray at night only; specimensmounted on kiln-dried white oak boards;unstrained specimens

45� angle south; specimensmounted on kiln-dried white oakboards; unstrained specimens





Tensile Strength 106.5a 107.1a 109.5a 106.9a 103.7a 106.5a 109.5a

Elongation at Break 100a 100a 100a 86.7a 90a 96.6a 82.2a

Note: (1) Known formulation with a 20-year history of proven weather performance.aTest method: ASTM D412.


Manufacturers and trade names: Exxon�Vistalon�, Lanxess Buna� EP.

Applications and uses: Impact modification,hose, tubing, weather strips, insulation, jacketing,single-ply roofing sheet, window gaskets, andsound deadening, solar pool panels and facerespirators.

Data for EPDM rubbers are found in Tables12.28e12.48 and Figs 12.20e12.27.

12.8 Epichlorohydrin Rubber

Epichlorohydrin rubbers (CO, ECO) includehomopolymer of epichlorohydrin and a copolymer

Table 12.30 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weathering of Black,Randomly Selected, Unstrained EPDM Terpolymer17

Exposure Conditions




Exposure Note Water spray at night only; specimensmounted on kiln-dried white oak boards;unstrained specimens

45� angle south; specimensmounted on kiln-dried white oakboards; unstrained specimens





Tensile Strength 96 92.7 97 97 97.8 992 100.3

Elongation at Break 105.8 962 92.3 83.7 98.1 92.3 82.7

Note: (1) Randomly selected samples from different manufacturers.

Table 12.31 Mechanical Properties Retained and Color Change after Outdoor Weathering, Accelerated OutdoorWeathering by EMMAQUA, and Accelerated Weathering with a Xenon Arc Weather-Ometer� for Black ExxonVistalon� EPDM Terpolymer14

Exposure Conditions

Exposure Type Outdoor weathering Accelerated outdoorweathering

Accelerated weathering

Exposure Location Arizona Arizona

Exposure Apparatus EMMAqua� Xenon arc Weather-Ometer�

Exposure Time (Days) 365 365 216

Exposure Note Water spray added


Tensile Strength 98.2 90.9 87.9

Elongation 66.8 34.4 20.8


DE Color Change 6.5 10.5 8.6


Table 12.32 Material Properties Retained and Color Change after Arizona Outdoor Weathering with and WithoutWater Spray Added for Black Exxon Vistalon� 5600 EPDM Terpolymer4


VistaIon 5600 100 100 100 100 100 100 100 100

DPTTS 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8

Flectol H (Monsanto) 1 1 1 1 1 1 1 1

Stearic Acid 2 2 2 2 2 2 2 2

TDEDC 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8

Thiotax (Monsanto) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Thiurad (Monsanto) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8

Naphthenic Process Oil 100 100 100 100 100 100 100 100

Sulfur 2 2 2 2 2 2 2 2

Zinc Oxide 5 5 5 5 5 5 5 5

N-550 Carbon Black 100 100 100 100 100 100 100 100

N-774 Black 100 100 100 100 100 100 100 100

Exposure Conditions

Exposure Note 5� angle 5� angle; with water spray (distilled watersprayed for 4 h proceeding

Sunrise and Then 20 Timesduring the Day in 15 sBursts



Tensile Strength, ASTMD412

97 100 111 99 94 98 109 87

Elongation, ASTM D412 65 67 48 47 60 67 49 52


Hardness Change (Units)ASTM D2240

6 6 11 11 6 6 11 14


DE Color Change 7 9.9 5.4 10.5 7.5 6.5 9.2 8.7

Note: (1) Outdoor weathering in Phoenix Arizona, test lab DSET Laboratories. (2) Shore A hardness 76. (3) Samplethickness (mm) 0.76.

Table 12.33 Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering of BlackExxon Vistalon� 5600 EPDM Terpolymer5


Vistalon� 5600 100 100 100 100

DPTTS 0.8 0.8 0.8 0.8

Flectol H (Monsanto) 1 1 1 1




Stearic Acid 2 2 2 2

TDEDC 0.8 0.8 0.8 0.8

Thiotax (Monsanto) 1.5 1.5 1.5 1.5

Thiurad (Monsanto) 0.8 0.8 0.8 0.8

Naphthenic Process Oil 100 100 100 100

Sulfur 2 2 2 2

Zinc Oxide 5 5 5 5

N-550 Carbon Black 100 100 100 100

N-774 Black 100 100 100 100

Exposure Conditions

Exposure Time (Days) 182 365 182 365

Exposure Note 5� south latitude 5� south latitude; water spray added


100% Modulus 132 134 138 134


Elongation at Break 66 68 60 66


DE Color Change, ASTMD412

7 10.1 7.4 6.5

Note: (1) Outdoor weathering in Phoenix Arizona, test lab DSET Laboratories. (2) Shore A hardness 76. (3) Samplethickness (mm) 0.76.

Table 12.34 Mechanical Properties Retained after Florida Outdoor Weathering and Accelerated OutdoorWeathering by EMMA for Black, Weather Resistant, Strained EPDM Terpolymer17

Exposure Conditions



Exposure Apparatus EMMA, Fresnel concentrator with 10mirrors

Exposure Note Water spray at night only; specimensmounted on kiln-dried white oak boards;specimens strained at 50%

45� angle south; specimensmounted on kiln-dried white oakboards; specimens strained at50%



(Continued )



Exposure Conditions




117.5 112.6 125.5 120.6 116.3 116.9 104

Elongation at Break, ASTMD412

91.1 70 67.8 722 72.2 65.6 46.7

Note: (1) Known formulation with a 20-year history of proven weather performance.

Table 12.35 Material Properties Retained and Color Change after Florida Outdoor Weathering with and WithoutWater Spray Added for Black Exxon Vistalon� 5600 EPDM Terpolymer18


Vistalon� 5600 100 100 100 100 100 100 100 100

OPUS 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8


Stearic Acid 2 2 2 2 2 2 2 2

TDEDC 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8




Sulfur 2 2 2 2 2 2 2 2

Zinc Oxide 5 5 5 5 5 5 5 5

N-550 Carbon Black 100 100 100 100 100 100 100 100

N-774 Black 100 100 100 100 100 100 100 100

Exposure Conditions

Exposure Note 5� angle 5� angle; with water spray (distilled water sprayedfor 4 h preceding sunrise and then 20 times duringthe day in 15 s bursts)




90 94 110 97 109 95

Elongation, ASTM D412 720 71 62 77 67 61


Hardness Change (Units),ASTM D2240

�1 1 9 13 6 8


DE Color Change, FMC-2Hunterlab; Test Method:SAE J1545

5.3 5.8 4.5

Note: (1) Outdoor weathering in Homestead, FL, test lab DSET Laboratories. (2) Shore A hardness 76. (3) Sample thickness(mm) 0.76.


Table 12.36 Material Properties Retained and Surface and Appearance after Florida Outdoor Weathering ofBlack, Medium Gloss Weatherable EPDM Terpolymer6

Exposure Conditions

Exposure Note Direct exposure; 5� south Under glass exposure; 5� south

Exposure Time (Days) 730 730


100% Modulus 115 132




Shore A Hardness Change(Units)

8 13


Gloss at 60� Retained(%);Gardner Gloss; TestMethod: ASTM D3134

57 14.3

DE Color 0.8 0.5

Visual Observation(As Weathered)

Slight chancing Severe mildew

Visual Observation (Washed) No chalking, no cracks Spotted, no cracks

Note: (1) Outdoor weathering in FL. (2) Shore A hardness 65. (3) Sample thickness (mm) 32.

Table 12.37 Mechanical Properties Retained after Florida Outdoor Weathering and Accelerated OutdoorWeathering by EMMA for Black, Randomly Selected, Strained EPDM Terpolymer17

Exposure Conditions



Exposure Apparatus EMMA, Fresnel concentrator with 10 mirrors Outdoor weathering

Exposure Note Water spray at night only; specimensmounted on kiln-dried white oak boards;specimens strained 0 50%

45� angle south; specimensmounted on kiln-dried white oakboards; specimens strained 0 50%





Tensile Strength 110 107.8 117.5 115.4 112.1 110.5 105.7

Elongation at Break 88.5 81.7 76.9 75 83.7 76 59.6



with ethylene oxide. There is also a terpolymer ofepichlorohydrin, ethylene oxide and a monomer tointroduce a carbon double bond to the chain thatfunctions as a cure site. CO is the ISO designation

for the homopolymer and ECO is the ISO desig-nation for the ethylene oxide copolymer. Epichlo-rohydrin terpolymer is the designation for theterpolymer (usually allyl glycidyl ether). The

Table 12.38 Mechanical Properties Retained after Florida Outdoor Weathering and Accelerated OutdoorWeathering by EMMA for White, Randomly Selected, Strained EPDM Terpolymer17

Exposure Conditions




Exposure Note Water spray at night only; specimensmounted on kiln-dried white oak boards;specimens strained at 50%

45� angle south; specimensmounted on kiln-dried white oakboards; specimens strained at50%





Tensile Strength 112.9 107 108.9 105.4 121.8 102 92.3

Elongation at Break 92 90 82 73 82 80 68


Table 12.39 Material Properties Retained and Color Change after Florida Outdoor Weathering of Black EPDMTerpolymer15

Exposure Conditions

Exposure Location Arizona Arizona Arizona Arizona Florida




148

Elongation, ASTM D412 44



24


DE Color Change(Samples Washed)

7.02 9.9 5.4 10.53


Table 12.40 Material Properties Retained and Color Change after Accelerated Outdoor Weathering by EMMAand EMMAQUA� and AcceleratedWeathering in a Xenon ArcWeather-Ometer� for Black Exxon Vistalon� 5600EPDM Terpolymer18


Vistalon� 5600 100 100 100 100 100 100 100 100

DPTTS 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8


Stearic Acid 2 2 2 2 2 2 2 2

TDEDC 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8




Sulfur 2 2 2 2 2 2 2 2

Zinc Oxide 5 5 5 5 5 5 5 5

N-550 Carbon Black 100 100 100 100 100 100 100 100

N-774 Black 100 100 100 100 100 100 100 100

Exposure Conditions

Exposure Type Accelerated weathering Accelerated outdoorweathering

Accelerated outdoorweathering

Exposure Apparatus Xenon arc Weather-Ometer� EMMA EMMAQUA

Exposure Note 89 �C; 3.8 h in light at 50%Relative Humidity (RH), 1 h indark at 100%RH; test method:SAE J1885; GM TM30-2


Energy at 340 nm (kJ/m2) 4703 7838

Energy 01 <380 nm(MJ/m2)

403 672



85 88 93 89 83 91 91 69

Elongation, ASTM D412 23 21 38 28 17 47 34 14



16 16 �1 12 19 15 13 22


DE Color Change, FMC-2Hunterlab; Test Method:SAE J1545

5.3 8.6 74 9.71 9.84 7.6 10.5 8.74

Note: (1) Shore A hardness 76. (2) Sample thickness (mm) 0.76.


Table 12.41 Mechanical Properties Retained and Color Change after Arizona Accelerated Outdoor Weatheringby EMMA and EMMAQUA� for Black Exxon Vistalon� 5600 EPDM Terpolymer19


Vistalon� 5600 100 100 100 100

DPTTS 0.8 0.8 0.8 0.8

Flectol H(Monsanto)

1 1 1 1

Stearic Acid 2 2 2 2

TDEDC 0.8 0.8 0.8 0.8

Thiotax(Monsanto)

1.5 1.5 1.5 1.5

Thiurad(Monsanto)

0.8 0.8 0.8 0.8

NaphthenicProcess Oil

100 100 100 100

Sulfur 2 2 2 2

Zinc Oxide 5 5 5 5

N-550 CarbonBlack

100 100 100 100

N-774 Black 100 100 100 100

Exposure Conditions

ExposureApparatus

EMMA EMMA EMMAqua� EMMAqua�

Exposure Time(Days)

182 365 182 365

Exposure Note Correlates toapproximately 2.5years of actualFlorida aging

Correlates toapproximately 5years of actualFlorida aging

Correlates toapproximately 2.5years of actualFlorida aging

Correlates toapproximately 5years of actualFlorida aging


100% Modulus 156


Elongation atBreak

38 29 47 35


DE ColorChange

5.3 8.6 74 9.71

Note: (1) Shore A hardness 76. (2) Sample thickness (mm) 0.76.


Table 12.42 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer for White, RandomlySelected, Strained EPDM Terpolymer17

Exposure Conditions

ExposureApparatus

Xenon arc Weather-Ometer� UV-CON

ExposureApparatus Note

Filter type: borosilicate inner and outer, spray nozzle: F-80;exposure: 0.35 W/m2 0340 nm

Lamp type: fluorescent UVB-313 (UVB-B)

Exposure CycleNote

690 min light, 30 min light and deionized water spray 20 h UV at 80 �C, 4 h condensation at 50 �C

Exposure TestMethod

ASTM 026 ASTM G53

Exposure Specimens mounted on exterior grade plywood covered withaluminum foil; specimen rotation every 250 h; specimensstrained at 50%

Specimens mounted on exterior grade plywood covered withaluminum foil; specimens strained at 50%

ExposureRelativeHumidity (%)

45e55 45e55 45e55 45e55 45e55

ExposureTemperature(�C, BlackPanel)

77e83 77e83 77e83 77e83 77e83

Exposure Time(Days)

20.8 41.7 83.3 125 166.6 20.8 41.7 83.3 125 166.6

Total Irradiation(MJ/m2)

711(calculated)

1422 2844 4266 5688 53(calculated)

106 213 319 425

UV Irradiation(MJ/m2)

72(calculated)

144 288 432 576 52(calculated)

103 206 310 413


Tensile Strength 105.4 102 96.9 10.9(samplebroke)

(samplebroke)

105.4 86.5 85.4 64.8(samplebroke)

21.8(samplebroke)

Elongation atBreak

91 80 79 32 (samplebroke)

(samplebroke)

99 87 90 48 (samplebroke)

16 (samplebroke)


12:ELASTOMERS

ANDRUBBERS

333

Table 12.43 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer� for White, RandomlySelected, Unstrained EPDM Terpolymer17

Exposure Conditions

Exposure Apparatus Xenon arc Weather-Ometer� UV-CON

Exposure ApparatusNote

Filter type: borosilicate inner and outer; spray nozzle:F-80; exposure: 0.35 W/m2 at 340 nm

Lamp type: fluorescent UVB-313 (UVB-8)

Exposure Cycle Note 690 min light, 30 min light and deionized water spray 20 h UV at 80 �C, 4 h condensation at 50 �C

Exposure Test Method ASTM G26 ASTM G53

Exposure Note Specimens mounted on exterior grade plywood coveredwith aluminum foil; specimen rotation every 250 h;unstrained specimens

Specimens mounted on exterior grade plywood covered withaluminum foil; unstrained specimens

Exposure RelativeHumidity (%)

45e55 45e55 45e55 45e55 45e55

Exposure Temperature(�C, Black Panel)

77e3 77e83 77e83 77e83 77e83

Exposure Time (Days) 20.8 41.7 83.3 125 166.6 20.8 41.7 83.3 125 166.6

Total Irradiation(MJ/m2)

711(calculated)

1422 2844 4266 5688 53(calculated)

106 213 319 425

UV Irradiation(MJ/m2)

72(calculated)

144 288 432 576 52(calculated)

103 206 310 413


Tensile Strength 91.7 86.5 76.8 64.2 29.8 92.8 84.8 86.5 48.1 31 (wide spread in testresults)

Elongation at Break 101 106 100 102 86 100 88 98 62 28 (wide spread in testresults)

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Table 12.44 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer� for Black, WeatherResistant, Strained EPDM Terpolymer17

Exposure Conditions


Exposure Apparatus Note Filter type: borosilicate inner and outer, spray nozzle: F-80;exposure: 0.35 Wm, at 340 nm




Exposure Note Specimens mounted on exterior grade plywood covered withaluminum foil; specimen rotation every 250 h; specimensstrained at 50%

Specimens mounted on exterior grade plywoodcovered with aluminum foil; specimens strained ay50%


45e55 45e55 45e55 45e55 45e55

Exposure Temperature(�C, Black Panel)

77e83 77e83 77e83 77e83 77e83

Exposure Time (days) 20.8 41.7 83.3 125 166.6 20.8 41.7 83.3 125 166.6

Total Irradiation (MJ/m2) 711 (calculated) 1422 2844 4266 5688 53 (calculated) 106 213 319 425

UV Irradiation (MJ/m2) 72 (calculated) 144 288 432 576 52 (calculated) 103 206 310 413



133.2 136 128 94.8 94.8 120 114.5 118.2 112 108.3

Elongation at Break, ASTMD412

77.8 67.8 46.7 36.7 37.8 88.9 72.2 66.7 36.7 37.8

Note: (1) Known formulation with a 20-year history of proven weather performance.

12:ELASTOMERS

ANDRUBBERS

335

Table 12.45 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer� for Black, RandomlySelected, Unstrained EPDM Terpolymer17

Exposure Conditions


Exposure Apparatus Note Filter type: borosilicate inner and outer; spray nozzle: F-80;exposure: 0.35 W/m2 at 340 nm




Exposure Note Specimen rotation every 250 h; unstrained specimens Unstrained specimens


45e55 45e55 45.55 45e55 45e55

Exposure Temperature(�C) (Black Panel Temp.)

77e83 77e83 77e83 77e83 77e83


Total Irradiation (MJ/m2)(calculated)

711 (calculated) 1422 2844 4266 5688 53 (calculated) 106 213 319 425



Tensile Strength 97 99.2 97 90.1 78.7 952 99.7 105.7 90 79.8

Elongation at Break 83.7 76 66.3 58.7 62.5 74 80.8 69.2 55.8 48

Note: (1) Randomly selected samples from different manufacturer; specimens mounted on exterior grade plywood covered with aluminum foil.

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monomers and polymer structures are given in Figs12.28e12.30.

The ratios of the monomers are tailored to providethe desired properties. The epichlorohydrinmonomerprovides heat and ozone resistance, fuel and oilresistance and gas permeation resistance. Theethylene monomer lowers the glass transitiontemperature, reduces heat resistance and impartsstatic dissipative properties. The unsaturated mono-mer introduces a site for sulfur and peroxide curing.

Manufacturers and trade names: Hercules, Inc.Herclor, B.F. Goodrich Co. and Zeon Chemicals,Hydrin�.

Applications and uses: Fuel hoses/liners (cells),air ducts, emissions tubing, electrostatic dissipativerolls, low-temperature fuel handling curb hose,diaphragms, gaskets/O-rings, vibration dampers,dust boots, closed-cell sponge and fabric coatings/belting.

Data for ECO are found in Figs 12.31e12.34.

12.9 Fluoroelastomers

A fluoroelastomer (FKM) is a special-purposefluorocarbon-based synthetic rubber. Whencompared to most other elastomers, it has widechemical resistance and superior performance,especially in high temperature application indifferent media. FKMs are categorized under theASTM D1418 & ISO 1629 designation of FKMs.The four main monomers that are used to makeFKMs are shown in Fig. 12.35.

The fluorine content is an important parameter ofeach FKM and is frequently reported in fact sheets.Most common grades have fluorine content thatvaries between 66% and 70%. Generally more fluo-rine means higher chemical resistance.

There are a number of types of FKMs.

� “A” type: FKM-A is the most widely used polymerin industry today, and it is the most cost-effectivepolymer in relationship toperformance. It has afluo-rine level around 66%. This elastomerwas designedin the late 1950s for the space program and today iswidely used as a general purpose FKM offeringexcellent fluid resistance to automotive fuels andlubricants, as well as elevated service temperatures.

� “B” type: FKM-B is a terpolymer with anincreased fluorine (68e69%) content is widelyused throughout the Chemical Processing andPower Generation Industries, “B” types are speci-fied for gaskets sealing mineral acids such assulfuric acids and other aggressive chemicalsthat are hauled by rail, and bulk tankers. “B” typescan be formulated with peroxide cure systems toresist strong acids, hot water and steam.

� “F” types: This terpolymer is the latest generationof “high” fluorine elastomers, with the addition of2% more fluorine, (70%) This is considered anexcellent elastomer for sealing today’s oxygenatedautomotive fuels and lubricants. “F” types can beformulated to resist concentrated aqueous inor-ganic acids, hot water, and steam.

Table 12.46 Mechanical Properties Retained and Color Change after Accelerated Weathering in a Xenon ArcWeather-Ometer� of Black Exxon Vistalon� 5600 EPDM Terpolymer19

Exposure Conditions


Exposure Temperature (�C) 89 89





DE Color Change 5.3a 8.8a

Note: (1) Sample thickness (mm) 0.76. (2) Shore A hardness 76. (3) Material composition (phr): Vistalon� 5600¼ 100,DPTTS¼ 0.8, Flectol H (Monsanto)¼ 1, stearic acid¼ 2, TDEDC¼ 0.8, Thiotax (Monsanto)¼ 1.5, Thiurad(Monsanto)¼ 0.8, naphthenic process oil¼ 100, sulfur¼ 2, zinc oxide¼ 5, N-550 carbon black¼ 100, N-774 black¼ 100.(4) Exposure test method: GM TM30. (5) Exposure Note: 3.8 h in light at 50% RH, 1 h in dark at 100% RH.aTest apparatus: Hunter colorimeter; test note: samples washed with water.


Table 12.47 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer� for Black, WeatherResistant, Unstrained EPDM Terpolymer17

Exposure Conditions

Exposure Apparatus Xenon arc Weather-Ometer� IN-CON

Exposure Apparatus Note Filter type: borosilicate inner and outer, spray nozzle: F-80;exposure: 0.35 W/m2 at 340 nm




Exposure Note Specimen rotation every 250 h; unstrained specimens Unstrained specimens


77e83 77e83 77-83 77e83 77e83





Tensile Strength 104� 100.3a 105.8� 89.8� 83.7� 103.4� 103.4� 105.5� 93.5� 85.5�

Elongation at Break 83.3a 75.13� 74.4� 48.9� 40� 88.9� 82.2� 71.1� 48.9� 422�

Note: (1) Known formulation with a 20-year history of proven weather performance; specimens mounted on exterior grade plywood covered with aluminum foil. (2)Relative humidity (%)¼ 45e55.aTest method: ASTM D412.

338

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EATHER

ONPLASTIC

SANDELASTOMERS

Table 12.48 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a Xenon Arc Weather-Ometer� of Black, RandomlySelected, Strained EPDM Terpolymer17

Exposure Conditions

Exposure Type Accelerated weathering Accelerated weathering


Exposure Apparatus Note Filter type: borosilicate inner and outer, spray nozzle: F-80;exposure: 0.35 W/m2 at 340 nm




Exposure Note Specimen rotation every 250 h; specimens strained at 50% Specimens strained at 50%


45e55 45e55 45e55 45e55 45e55


77e83 77e83 77e83 77e83 77e83





Tensile Strength 118.6 119.1 114.3 101.9 105.1 114 116.2 112.9 110 98

Elongation at Break 71.7 64.5 55.8 52.9 49 73.1 76 61.5 51.9 442

Note: (1) Specimens mounted on exterior grade plywood covered with aluminum foil.

12:ELASTOMERS

ANDRUBBERS

339

Figure 12.20 Carbonyl formationafter xenon arc Weather-Ometer� exposure of EPDMterpolymer.20

Figure 12.21 Decrease in molec-ular weight after xenon arcWeather-Ometer� exposure ofEPDM terpolymer.20

Figure 12.22 Relative change inelongation at break vs. exposurein xenon test DIN 53387 fora typical EPDM resin.21


Figure 12.23 Micro-IRHD hard-ness change vs. QUV� exposureof EPDM compound.16

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps with a blackpanel temperature of 45 �C anda cycle of 4 h condensation and4 h dry (3 cycles per day).

Figure 12.24 Tensile strengthchange vs. QUV� exposure ofEPDM compound.16

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps witha black panel temperature of45 �C and a cycle of 4 h condensa-tion and 4 h dry (3 cycles per day).

Figure 12.25 Elongation at breakvs. QUV� exposure of EPDMcompound.16

Note: Test pieces were exposedin QUV� fluorescent tube appa-ratus using UVA 340A lampswith a black panel temperatureof 45 �C and a cycle of 4 hcondensation and 4 h dry (3cycles per day).


Figure 12.26 Modulus at 100% vs. QUV� exposure of EPDM compound.16

Note: Test pieces were exposed in QUV� fluorescent tube apparatus using UVA 340A lamps with a black paneltemperature of 45 �C and a cycle of 4 h condensation and 4 h dry (3 cycles per day).

Figure 12.27 Modulus at 300% vs. QUV� exposure of EPDM compound.16


Figure 12.28 Epichlorohydrin homopolymer (CO) monomer and polymer structure.


Figure 12.29 Epichlorohydrin copolymer (ECO) monomers and polymer structure.

Figure 12.30 Epichlorohydrin terpolymer (GECO) monomers and polymer structures.

Figure 12.31 Micro-IRHD hardness change vs. QUV� exposure of typical epichlorohydrin rubber compound.16



Figure 12.33 Elongation at breakvs. QUV� exposure of typical epi-chlorohydrin rubber compound.16


Figure 12.34 Modulus at 100% vs.QUV� exposure of typical epichlo-rohydrin rubber compound.16


Figure 12.32 Tensile strengthchange vs.QUV� exposure of typicalepichlorohydrin rubber compound.16

Note: Test pieces were exposed inQUV� fluorescent tube apparatususing UVA 340A lamps with a blackpanel temperature of 45 �C anda cycle of 4 h condensation and 4 hdry (3 cycles per day).


� Viton� GF fluorocarbons are tetrapolymerscomposed of TFE (tetrafluoroethylene), VF2(vinyl fluoride), HFP (hexafluoropropylene), andsmall amounts of a cure site monomer. Presenceof the cure site monomer allows peroxide curingof the compound, which is normally 70% fluorine.As the most fluid resistant of the various FKMtypes, Viton� GF compounds offer improved resis-tance to water, steam, and acids.

� Viton� GFLT fluorocarbons are similar toViton� GF, except that perfluoromethylvinyl

ether (PMVE) is used in place of HFP. The“LT” in Viton� GFLT stands for “low tempera-ture.” The combination of VF2, PMVE, TFE,and a cure site monomer is designed to retainboth the superior chemical resistance and highheat resistance of the G-series fluorocarbons. Inaddition, Viton� GFLT compounds (typically67% fluorine) offer the lowest swell and thebest low-temperature properties. Viton� GFLTcan seal in a static application down to approxi-mately �40 �F.

� Fluorosilicone (FVMQ) is covered in the sectionon polysiloxanes/silicones.

� Perfluorinated elastomers (FFKM): This family ofelastomers is widely known by the trade name thatits inventors gave it, Kalrez�. It is essentially anelastomeric form of PTFE and retains the extremechemical resistance at temperature of PTFE up to327 �C.

� AFLAS�, made by Asahi Glass Co., Ltd, isa copolymer of tetrafluoroethylene and propylene.The fluorine content is typically 57%.

The FKMs are cured by several chemical means asdescribed in Tables 12.49 and 12.50.

Figure 12.35 Monomers used to makefluoroelastomers.

Table 12.49 Curing Chemistry of Fluoroelastomers

FKM Type Monomers Curable By: Recommended Curative

Copolymer VF2, HFP Amine, bisphenol Bisphenol

Terpolymer VF2, HFP, TFE Amine, bisphenol Bisphenol

Peroxide Curable VF2, HFP, TFE, CSM Amine, bisphenol, peroxide Peroxide

Low Temperature VF2, HFP, TFE, PMVE,CSM

Amine, bisphenol, peroxide Peroxide

Table 12.50 The Curing Chemistry Used by Solvay Solexis Tecnoflon� Fluoroelastomer Products

Grade Fluorine Content (%)10% Temperature of

Retractiona (�C) Cure Type

T 636 66 �19 Bisphenol A

L636 65 �21 Bisphenol A

PL 458 67 �24 Peroxide





PL 855 65 �30 PeroxideaAn industry standard for determining the ability of an elastomer to seal.


Manufacturers and trade names: DyneonFluorel�, Solvay Solexis Technoflon�, DuPontViton�, Kalrez�, Daikin Dai-el�, Asahi GlassAFLAS�.Applications: Seals, caulks, coatings, vibration

dampeners, expansion joints, gaskets, O-rings, pistonseals, custom shapes, and stock rod and sheet.The FKM data are found in Figs 12.36e12.39.

12.10 Natural Rubber

Natural rubber is polyisoprene. The structure ofthe monomer and polymer are given in Fig. 12.40. ItsCAS number is 9006-04-6. Chemical and environ-mental resistance and mechanical properties areimproved through cross-linking (vulcanizing),usually through treatment with sulfur.Natural rubber is more unsaturated and has fewer

methyl groups thanbutyl rubber causing it tobe20 timesmore permeable to air. The presence of methyl groupsgenerally serves to reduce the permeability of polymers.Epoxidized natural rubber is derived from the

partial epoxidation of the natural rubber molecule,resulting in a totally new type of elastomer. Theepoxide groups are randomly distributed along thenatural rubber molecule.Epoxidation results in a systematic increase in the

polarity and glass transition temperature. Propertychanges with increasing level of epoxidation include:

� An increase in damping

� A reduction in swelling in hydrocarbon oils

� A decrease in gas permeability

� An increase in silica reinforcement; improvedcompatibility with polar polymers like polyvinylchloride

� Reduced rolling resistance and increased wet grip

Applications and uses: Tire and other automotive.The natural rubber data are found in Figs

12.41e12.50.

12.11 AcrylonitrileeButadieneCopolymer

Acrylonitrileebutadiene copolymers (NBR) com-monly called nitrile rubbers are copolymers ofbutadiene and acrylonitrile. The monomers andpolymer structure are shown in Fig. 12.51. The CASnumber is 9003-18-3.NBR is commonly considered the workhorse of

the industrial and automotive rubber productsindustries. NBR is actually a complex family ofunsaturated copolymers of acrylonitrile andbutadiene. The amount of acrylonitrile in thepolymer is used to manipulate the balance ofNBR properties. Acrylonitrile content may rangefrom 18% to 50%. Increasing acrylonitrilecontent leads to higher hardness, strength, abra-sion resistance, heat resistance, and oil/fuelresistance, and lower resilience and low-tempera-ture flexibility.There are several general types of NBR:

� Cold NBRdAcrylonitrile content ranges from15% to 51%. Cold polymers are polymerized at

Figure 12.36 Micro-IRHD hard-ness change vs. QUV� exposureof DuPont Viton� A200C fluoroe-lastomer.16



Figure 12.37 Tensile strengthchange vs. QUV� exposure ofDuPont Viton� A200C fluoroelasto-mer.16


Figure 12.38 Elongation at breakvs. QUV� exposure of DuPontViton� A200C fluoroelastomer.16


Figure 12.39 Modulus at 100% vs.QUV� exposure of DuPont Viton�

A200C fluoroelastomer.16



Figure 12.40 Structure of isoprene and polyisoprene.

Figure 12.41 Micro-IRHD hardness change vs. QUV� exposure of Natural Rubber.16


Figure 12.42 Tensile strength change vs. QUV� exposure of natural rubber.16



Figure 12.43 Elongation atbreak vs. QUV� exposure ofnatural rubber.16

Note: Test pieceswere exposedin QUV� fluorescent tube appa-ratus using UVA 340A lampswith a black panel temperatureof 45 �C and a cycle of 4 hcondensation and 4 h dry(3 cycles per day).

Figure 12.44 Modulus at100% vs. QUV� exposure ofnatural rubber.16


Figure 12.45 Modulus at300% vs. QUV� exposure ofnatural rubber.16



Figure 12.46 Micro-IRHDhardness change vs. QUV�

exposure of mineral-fillednatural rubber.16

Note: Test pieces wereexposed in QUV� fluorescenttube apparatus using UVA340A lamps with a black paneltemperature of 45 �C anda cycle of 4 h condensationand 4 h dry (3 cycles per day).

Figure 12.47 Tensile strengthchange vs. QUV� exposure ofmineral-filled natural rubber.16


Figure 12.48 Elongation at breakvs. QUV� exposure of mineral-filled natural rubber.16



Figure 12.49 Modulus at 100% vs. QUV� exposure of mineral-filled natural rubber.16


Figure 12.50 Modulus at 300% vs. QUV� exposure of mineral-filled natural rubber.16


Figure 12.51 Monomers and polymer structure of NBR.


a temperature range of 5e15 �C, depending on thebalance of linear-to-branched configurationdesired. The lower polymerization temperaturesyield more-linear polymer chains.

� Hot NBRdPolymers are polymerized at thetemperature range of 30e40 �C. This processyields highly branched polymers. Branchingsupports good tack and a strong bond in adhesiveapplications. The physically entangled structureof this kind of polymer also provides a significantimprovement in hot tear strength compared witha cold-polymerized counterpart. The hot polymer’snatural resistance to flow makes them excellentcandidates for compression molding and sponge.Other applications are thin-walled or complexextrusions where shape retention is important.

� Cross-linked hot NBRdThese are branched poly-mers that are further cross-linked by the additionof a difunctional monomer. These products aretypically used in molded parts to provide sufficientmolding forces, or back pressure, to eliminatetrapped air. Another use is to provide increaseddimensional stability or shape retention forextruded goods and calendered goods. This leadsto more efficient extruding and vulcanization ofintricate shaped parts as well as improved releasefrom calender rolls. These NBRs also add dimen-sional stability, impact resistance and flexibilityfor PVC modification.

� Carboxylated nitriledAddition of carboxylic acidgroups to the NBR polymer’s backbone signifi-cantly alters processing and cured properties.The result is a polymer matrix with significantlyincreased strength, measured by improved tensile,tear, modulus and abrasion resistance. The nega-tive effects include reduction in compression set,water resistance, resilience and some low-temper-ature properties.

� Bound antioxidant NBRdan antioxidant is poly-merized into the polymer chain. The purpose isto provide additional protection for the NBRduring prolonged fluid service or in cyclic fluidand air exposure. When compounding with highlyreinforcing furnace carbon black the chemicalreactivity between the polymer and the pigmentcan limit hot air-aging capability. Abrasion resis-tance is improved when compared with conven-tional NBR, especially at elevated temperatures.They have also been found to exhibit excellentdynamic properties.

� Hydrogenated nitrile butadiene rubber (HNBR),also known as highly saturated nitrile, is specialclass of nitrile rubber (NBR) that has been hydro-genated to increase saturation of the butadienesegment of the carbon polymer backbone. Thismeans that many of the carbonecarbon doublebonds are changed to single bonds with the addi-tion of hydrogens to those carbons. Carbonecarbon single bonds are more flexible that doublebonds. Subsequent improvements to the materialproperties, over that of a nitrile rubber (NBR),include greater thermal stability, broader chemicalresistance and greater tensile strength.

Manufacturers and trade names: LanxessPerbunan�, Krynac� and Baymod� N, Girsa,Hyundai, JSR Corporation, Kumho, Nantex, Nitri-flex, PetroChina, Petroflex, Polimeri Europa Euro-prene, Zeon Chemicals Zetpol�.Applications and uses: nonlatex gloves for the

healthcare industry, automotive transmission belts,hoses, O-rings, gaskets, oil seals, V-belts, syntheticleather, printer’s roller and as cable jacketing.The NBR rubber data are found in Table 12.51 and

Figs 12.52e12.61.

12.12 StyreneeButadiene Rubber

Styreneebutadiene or styreneebutadiene rubber(SBR)22 is a synthetic rubber copolymer consistingof styrene and butadiene, and its structure is shown inFig. 12.62.Manufacturers and trade names: Lanxess

Krylene� and Krynol� and many others.Applications and uses: Employed extensively in

almost all sectors of the rubber industry. Used mainlyfor tires, often in blends with natural rubber; con-veyor and transmission belting, footwear soles andheels; technical goods of all kinds, e.g. seals,membranes, hose and rolls.SBR 1500 is a high-molecular-weight SBR

combining good extrusion behavior and superiorcompound properties. It has relatively wide molec-ular weight distribution and the butadiene compo-nent has an average about 9% Cis-1,4; 54.5% transand 13% 1,2 vinyl structure. SBR 1500 containsantioxidant to avoid product degradation. The highstrength and great toughness of rubber permit the useof its elastic qualities. The properties of rubber showexcellent resistance to cutting, tearing and abrasion.


Table 12.51 Material Properties after Florida Outdoor Weathering of Eliokem Chemigum� TPE 2175 NitrileThermoplastic Elastomer21


Sample Thickness (mm) 32 32

Exposure Conditions

Exposure Note Direct exposure; 5� south Under glass exposure; 5�

south



100% Modulus 97 97




Shore A Hardness Change(Units)

0 0


Gloss at 60� Retained (%) 12.6a 301a

DE Color 2.28b 1.46b

Visual Observation(As Weathered)

Slight chalking No blemish

Visual Observation(Washed)

No chalking, no cracks Clean, no cracks

Note: (1) Black color, medium gloss. (2) Compression molding.aTest name: Gardner gloss; test method: ASTM D3134.bTest method: SAE J545.


exposure of NBR rubbers.16



Figure 12.53 Tensile strengthchange vs. QUV� exposure ofNBR rubbers.16


Figure 12.54 Elongation atbreak vs. QUV� exposure ofNBR rubbers.16


Figure 12.55 Modulus at100% vs. QUV� exposure ofNBR rubbers.16



Figure 12.56 Modulus at300% vs. QUV� exposure ofNBR rubbers.16



exposure of Zeon ChemicalsZetpol� HNBR rubbers.16


Figure 12.58 Tensile strengthchange vs. QUV� exposure ofZeon Chemicals Zetpol�

HNBR rubbers.16



Figure 12.59 Elongation atbreak vs. QUV� exposure ofZeon Chemicals Zetpol�

HNBR rubbers.16


Figure 12.60 Modulus at100% vs. QUV� exposure ofZeon Chemicals Zetpol�

HNBR rubbers.16


Figure 12.61 Modulus at300% vs. QUV� exposure ofZeon Chemicals Zetpol�

HNBR rubbers.16



It has a relatively long, useful life under a widevariety of conduction.

The SBR rubber data are found in Figs12.63e12.72.

12.13 EthyleneeVinyl AcetateCopolymer

Ethyleneevinyl acetate copolymer (EVA) isa copolymer of ethylene and vinyl acetate as shownin Fig. 12.73. These polymers have several “short-hand” identifiers including EVAC, EVA, E/VA,E/VAC and EVM. Its CAS number is 24937-78-8.

Figure 12.62 Structure of SBR.


exposure of SBR 1500rubber.16


Figure 12.64 Tensile strengthchange vs. QUV� exposure ofSBR 1500 rubber.16



Figure 12.65 Elongation atbreak vs. QUV� exposure ofSBR 1500 rubber.16


Figure 12.66 Modulus at100% vs. QUV� exposure ofZeon Chemicals SBR 1500rubber.16








Figure 12.69 Tensilestrength change vs. QUV�


Note: Test pieces wereexposed in QUV� fluorescenttube apparatus using UVA340A lamps with a blackpanel temperature of 45 �Cand a cycle of 4 h condensa-tion and 4 h dry (3 cycles perday).

Figure 12.70 Elongation atbreak vs. QUV� exposure ofSBR 1710 rubber.16



Commercial resins range in vinyl acetate contentfrom 7.5 wt% to 33 wt%. Some grades are availablewith antiblock and slip additives. DuPont� Elvax�

grades vary by vinyl acetate content.

EVA properties vary depending on vinyl acetatecontent:Higher vinyl acetate content:

� Increased gas permeability





Figure 12.73 Structure of EVApolymers.


� Increased impact strength-toughness

� Improved optical qualities-clarity

� Increased flex-crack resistance

� Increased cling

� Increased solubility

� Increased coefficient of friction

� Decreased sealing temperature-softening point

� Increased crystallinity

� Reduced stiffness

� Reduced surface hardness

Weathering: The major decomposition reactionsare deacetylation or what is called a Norrish IIreaction (shown at the top of Fig. 12.74) and hemo-lytic dissociation or what is called a Norrish I reac-tion (shown at the bottom for Fig. 12.74). Increasedconcentration of vinyl acetate in the EVA polymercontributes to a long-term increased stability ofunstabilized copolymer.

Products of photodegradation include hydroper-oxides, hydroxyl groups, polyene sequences, alde-hyde and acetic acid. Typical results ofphotodegradation are yellow-brown discolorationand loss of mechanical properties.


� Ultraviolet Absorber (UVA): such as 2-hydroxy-4-octyloxybenzophenone;

� Hindered Amine Stabilizer: such as 1,3,5-triazine-2,4,6-triamine, N,N000[1>,2-ethane-diyl-bis[[[4,6-bis[butyl(1,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]bis[N0,N00-dibutyl-N0,N00-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-;

� Phenolic antioxidant: such as pentaerythritol tet-rakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate);

� Amine: such as benzenamine, N-phenyl-, reactionproducts with 2,4,4-trimethylpentene;

� Optical brightener: 2,20-(1,2-ethylenediyldi-4,1-phenylene)bisbenzoxazole, C.I.F.B. 3671;

� Manufacturers and trade names: DuPont�Appeel� and Elvax�, Celanese EVA PerformancePolymers Ateva�, Lanxess Levapren�,Baymond� L and Levamelt�, Arkema Evatane�.

� Applications and uses: automotive, machinery,building/construction, wire and cable, sportinggoods and photovoltaic modules.

Data for EVA elastomers are found in Figs12.75e12.79.

12.14 Polysulfide Rubber

Polysulfide rubber is a synthetic rubber that isa product of the polycondensation of dihalides ofaliphatic compounds (for example, ethylenedichloride or propyl dichloride) with polysulfides ofalkali metals (for example, Na2Sx, where x¼ 2e4).Polysulfide rubbers are divided into polytetrasulfidesand polydisulfides, with the general formulas[eReSeSeSeSe]n and [eReSeSe]n, shown inmore detail in Fig. 12.80.

The curing of liquid polysulfide polymers to high-molecular-weight elastomers is normally accom-plished by oxidizing the polymer’s thiol(eSH)terminals to disulfide (eSeSe) bonds as shown inFig. 12.81. H2O the curing agents most commonlyused are oxygen-donating materials such as

Figure 12.74 Major EVA polymer degradation pathways.


Figure 12.75 Relative changeof elongation at break (%) ofLanxess Levapren � EVA.24

Note: Xenon Test DIN 53, 387.


exposure of LanxessLevapren� 400 EVA rubber.16


Figure 12.77 Tensile Strengthchange vs. QUV� exposure ofLanxess Levapren� 400 EVArubber.16



manganese dioxide, calcium peroxide, cumenehy-droperoxide and p-quinone dioxime.

Polysulfide rubbers are produced in solid andliquid forms (high-molecular-weight and low-

molecular-weight rubbers, respectively), and also asaqueous dispersions, or lattices.

Polysulfide rubbers are special-purpose polymerscharacterized by high resistance to swelling in solvents,fuels and oils; resistance to sunlight; moisture and gasimpermeability; and stability during storage. Theseproperties result from the high sulfur content and theabsence of unsaturated bonds in the macromolecules.Themolecular weight of solid rubbers is (200e500)�

Figure 12.78 Elongation atbreak vs. QUV� exposure ofLanxess Levapren� 400 EVArubber.16

Note: Test pieces wereexposed in QUV� fluorescenttube apparatus using UVA340A lamps with a blackpanel temperature of 45 �Cand a cycle of 4 h condensa-tion and 4 h dry (3 cycles perday).

Figure 12.79 Modulus at100% vs. QUV� exposure ofLanxess Levapren� 400 EVArubber.16


Figure 12.80 Structure of a typical polysulfide rubber resin.

Figure 12.81 Cure/cross-linking reaction of polysul-fide resin with oxygen.


103; density, 1.27e1.60 g/cm3; glass transition point,e23 �C toe57 �C.Zinc oxide, p-quinonedioxime, anda mixture of Altax and diphenylguanidine are used tovulcanize polysulfide rubbers. Vulcanized polysulfiderubbers are inferior in mechanical properties to thosemade from other synthetic rubbersdfor example, theirtensile strength is 6e10 MN/m2; relative elongation,200e400 percent.Polysulfide rubbers are used in rubberizing fuel

storage tanks and in the manufacture of oil- andgasoline-resistant tubing and of gastight diaphragmsfor gas meters. Sealing compounds are preparedfrom liquid Thiokols. The most important

commercial polysulfide rubbers are Thiokol DA(USSR) and Thiokol A, FA and ST (USA).Data for polysulfide rubbers are found in Figs

12.82e12.85.

12.15 Polysiloxane/SiliconeRubber

Silicones are also known as siloxanes, poly-organosiloxanes, or polysiloxanes. Silicone rubber isa semi-organic synthetic. Its polymer backbonestructure consists of a chain of silicon and oxygen


exposure of polysulfiderubber.16


Figure 12.83 Tensile strengthchange vs. QUV� exposure ofpolysulfide rubber.16



atoms rather than carbon and hydrogen atoms, as inthe case with other types of rubber. The molecularstructure of silicone rubber results in a very flexible-dbut weakdchain. Silicones are very stable at lowand high temperatures. Although fillers may improveproperties somewhat, tear and tensile strengths remainrelatively low. Figure 12.86 shows four of the primarygroups that make up a typical polysiloxane. To simplythe discussion of polysiloxane composition, themonomers are identified by letters:

Some common abbreviations for the polymersinclude: MQ, VMQ, PMQ, PVMQ, PDMS

Figure 12.84 Elongation atbreak vs. QUV� exposure ofpolysulfide rubber.16


Figure 12.85 Modulus at100% vs. QUV� exposure ofpolysulfide rubber.16


Figure 12.86 Structure of groups that make up poly-siloxanes, “M” stands for Me3SiO, “D” for Me2SiO2,“T” for MeSiO3, “Q” for SiO4 “P” for replace Me withphenyl side groups “V” for replace Me with vinylside groups (typically <1%) “F” for replace Me withfluorine.


(polydimethylsiloxane). See Figure 12.86 for mostletter designations.The curing chemistry affects the properties of

silicone rubbers. Three common curatives used inFigs 14.25e14.39 are:

� Platinum-cured liquid silicone rubber (LSR),Wacker Chemie AG Elastosil� LR3003/50 LSR,Part A & B liquid system;

� Platinum-cured high-consistency rubber (platinum-cured HCR), Wacker Chemie AG Elastosil�

R4000/50; and

� Peroxide-cured high-consistency rubber (peroxide-cured HCR), GE Bayer Silicones GmbH & Co.KGHV3622, cured byDi-2,4-dichlorobenzoylper-oxide with 1% loading.

Table 12.52 Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for Dow CorningSilastic� Silicone Rubber23

Exposure Location Michigan Michigan Michigan Florida

Exposure Time 1 year 2 years 5 years 20 years

Property Change

Tensile Strength (%) þ8 to �25 þ4 to �22 þ22 to �27 �31

Elongation (%) þ4 to �28 þ14 to �34 �55

Hardness (Point Change) þ3 to �6 þ2 to �6 þ8 to �9 þ7

Note: (1) Exposure conditions ASTM D518, method A.

Table 12.53 Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for Dow CorningSilastic� Silicone Rubber23

Exposure Location Michigan Michigan Michigan Florida

Exposure Time 1 year 2 years 5 years 20 years

Property Change

Tensile Strength (%) 0 to �23 �8 to �42 �14 to �54 �41

Elongation (%) þ4 to �40 0 to �45 �24 to �50 �60

Hardness (Point Change) þ1 to �8 �3 to �16 þ5 to �8 þ2

Note: (1) Exposure conditions ASTM D518, method B.


exposure of silicone rubber.16



Peroxide curing gives an end product that is morerigid, more resilient with methyl and vinyl cross-links. Platinum curing gives an end product that ismore flexible with better tear with vinyl/hydridecross-links.

Manufacturers and trade names: Bayer Corpo-ration Baysilone�; Shincor Silicones KE�; Dow

Corning Corp. Silastic�; General Electric Silplus�,Tufel�, SE; Rhone-Poulenc Inc. Rhodorsil, WackerChemie AG Elastosil�.

Data for Polysiloxanes are found in Tables 12.52and 12.53 and Figs 12.87e12.94.

Figure 12.88 Tensile strength change vs. QUV� exposure of silicone rubber.16


Figure 12.89 Elongation at break vs. QUV� exposure of silicone rubber.16



Figure 12.90 Modulus at100% vs. QUV� exposure ofsilicone rubber.16



exposure of silicone FVMQrubber.16


Figure 12.92 Tensile strengthchange vs. QUV� exposure ofsilicone FVMQ rubber.16



References

1. McKeen LW. The effect of temperature and otherfactors on plastics, plastics design library. Wil-liam Andrew Publishing; 2008.

2. Drobny Jiri George. Handbook of thermoplasticelastomers. William Andrew; 2007. p. 215e234.

3. A guide to thermoplastic polyurethanes (TPU).Huntsman Chemical; 2010.

4. Estane thermoplastic polyurethane product datasheets, supplier technical report (BFG-15512-J).The BFGoodrich Company.

5. UV stabilization of aromatic pellethane ther-moplastic polyurethane elastomers, supplier

technical report (306-00439-1293 SMG). DowChemical Company; 1993.

6. Elastollan design and processing guide, supplierdesign guide. BASF Corporation; 1993.


8. Weathering of Santoprene thermovulcanizateblack ultraviolet grades, Santoprene specialtyproducts. Exxon Mobil Chemical Co.; 1992.

9. Forprene by S.O.F.TER., supplier marketingliterature (RDS 049/9240). Evode Plastics.

10. Drobny Jiri George. Handbook of thermo-plastic elastomers. William Andrew; 2007.p. 249e264.

Figure 12.93 Elongation atbreak vs. QUV� exposure ofsilicone FVMQ rubber.16


Figure 12.94 Modulus at100% vs. QUV� exposure ofsilicone FVMQ rubber.16



11. Hytrel technical notesdWeather protection ofHytrel with carbon black, supplier technicalreport (1e48). DuPont Company.

12. Pigmentation and weathering protection ofHytrel, supplier technical report (HYT-303(R1)/E-73191). DuPont Company; 1985.

13. Hytrel design guidedModule V. DuPont; 2000.14. Weatherability of Santoprene rubber compared

to other materials, supplier technical report(TCD01588). Advanced Elastomer Systems; 1988.

15. Set a new standard of performance for yournon-residential glazing seals, supplier marketingliterature. Advanced Elastomer Systems; 1993.

16. Brown RP, Butler T, Hawley SW. Ageing ofrubberdAccelerated weathering and ozone testresults. Smithers Rapra Technology; 2001.

17. Gish BD, Jablonowski TL. Weathering tests forEPDM rubber sheets for use in roofing appli-cations, 8th Conference on Roofing Technology,

conference proceedings. National Bureau ofStandards and NRCA; 1987.

18. Weathering of Santoprene thermoplastic rubberblack ultraviolet grades, supplier technical report(TCD00592). Advanced Elastomer Systems;1992.

19. Weathering data of Santoprene thermoplasticrubber (black grades) versus standard thermosetrubbers, supplier technical report (TCD03787).Monsanto Company; 1987.

20. Engage polyolefin elastomers, supplier marketingliterature (305-01995-1293SMG). DowChemicalCompany; 1993.

21. LEVAPREN� ethylene vinyl acetate (EVM) thecost-effective specialty rubber. Lanxess; 2005.


23. Rubber physical and chemical properties. DowCorning Corporation; 2005.


13 Sustainable Polymers

13.1 Sustainable Polymers

Polymers may be classified as sustainable plasticby several means including:

(1) Recycling the waste plastic;

(2) Manufacturing from renewable raw materials;and

(3) Biodegradable in landfills.

The ideal sustainable plastic is of renewable bio-logical origin, maybe be recycled if desired andbiodegradable at the end of its life. Environmentallyfriendly or “green” polymers are those that areproduced from renewable resource rawmaterials suchas corn or that are biodegradable or compostable. Thisis a developing area in packagingmaterials and thoughthere are a relatively limited number of polymers usedcommercially, they will certainly become morenumerous and more common in the future.

Biodegradable plastics are made out of ingredientsthat can be metabolized by naturally occurringmicroorganisms in the environment. Some petroleum-based plastics will biodegrade eventually, but thatprocess usually takes a very long time and contri-butes to global warming through the release of carbondioxide.

Petroleum-based plastic is derived from oil,a limited resource. Plastic based in renewable rawmaterials biodegrade much faster and can be almostcarbon neutral. Renewable plastic is derived fromnatural plant products such as corn, oats, wood andother plants, which helps ensure the sustainability ofthe earth. Polylactic acid (PLA) is the most widelyresearched and used 100% biodegradable plastic-packaging polymer currently, and is made entirelyfrom corn-based cornstarch. Details on PLA areincluded in a following section.

Cellophane� is a polymeric cellulose film madefrom the cellulose from wood, cotton, hemp or othersources. There are several modifications made tocellulose called polysaccharides (cellulose esters)that are common including cellulose acetate,

nitrocellulose, carboxymethyl cellulose and ethylcellulose. Details on Cellophane� and its derivativesare included in several following sections.

Polycaprolactone (PCL) is biodegradable poly-ester that is often mixed with starch. Details on PLAare included in a following section.

Several interesting green polymers are discussedin the next few paragraphs. These are ones for whichno public weathering data have been identified.

Polyanhydrides currently are used mainly in themedical device and pharmaceutical industry.1

Figure 13.1 shows the generalized structure of ananhydride polymer and two polyanhydrides that areused to encapsulate certain drugs. The poly(bis car-boxyphenoxypropane) (pCCP) is relatively slow todegrade. The poly(sebacic anhydride) (pSA) is fastto degrade. Separately neither of these materials canbe used, but if a copolymer is made in which 20% ofthe structure is pCCP and 80% is pSA, the overallproperties meet the needs of the drug. Poly-anhydrides are now being offered for general uses.

Figure 13.1 Polyanhydride chemical structures.

The Effect of UV Light and Weather on Plastics and Elastomers, 3e. http://dx.doi.org/10.1016/B978-1-4557-2851-0.00013-X


http://dx.doi.org/http://dx.doi.org/10.1016/B978-1-4557-2851-0.00013-X

Polyglycolic acid (PGA) and its copolymers havefound limited use as absorbable sutures and are beingevaluated in the biomedical field, where its rapiddegradation is useful. That rapid degradation haslimited it use in other applications. The structure ofPGA is shown in Fig. 13.2.Polyhydroxyalkanoates (PHAs) are naturally

produced, and includepoly-3-hydroxybutyrate (PHB),polyhydroxyvalerate and polyhydroxyhexanoate;a PHA copolymer called (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is less stiff and tougher, and itmay be used as packaging material. Chemical struc-tures of some of these polymers are shown in Fig. 13.3.Interest in the “green” materials is strong as the

number of commercially available materials grows.Table 13.1 lists some of the commercial materialsrecently available.The following sections contain the details of

several of the more common sustainable polymers.

13.2 Cellulose-Based Materials

Cellulose is an organic compound with theformula (C6H10O5)n, the structure of which isshown in Fig. 13.4. It is a polysaccharide consist-ing of a linear chain of several 100 to over 10,000linked D-glucose units. Cellulose is mainlyobtained from wood pulp and cotton. Cellulose ischemically modified to make many polymersthat are useful in plastics or coatings. Some ofthese modifications are described in subsequentsections.Cellulose-based plastics are generally biode-

gradable and they are degraded by UV. Chainscission and various radicals can be produced asshown in Fig. 13.5. The macroradicals can reactwith oxygen producing hydroperoxide and otherdecomposition products as is common in many ofthe other plastics. In spite of these reactionpossibilities, cellulose is a relatively stable mate-rial.

13.2.1 Cellophane�Cellophane� is a polymeric cellulose film made

from the cellulose from wood, cotton, hemp or othersources. The raw material of choice is called dis-solving pulp, which is white like cotton and contains92e98% cellulose. The cellulose is dissolved inalkali in a process known as mercerization. It isaged several days. The mercerized pulp is treatedwith carbon disulfide to make an orange solutioncalled viscose, or cellulose xanthate. The viscosesolution is then extruded through a slit into a bath ofdilute sulfuric acid and sodium sulfate to reconvertthe viscose into cellulose. The film is then passedthrough several more baths, one to remove sulfur,one to bleach the film, and one to add glycerinto prevent the film from becoming brittle. Theapproximate chemical structures are shown inFig. 13.6.The Cellophane� may be coated with nitrocellu-

lose or wax to make it impermeable to water vapor. Itmay also be coated with polyethylene or othermaterials to make it heat sealable for automatedwrapping machines.Weathering: Viscose is largely transparent to UV

light but prolonged exposure to sunlight weakensviscose rayon fibers. A 6 h exposure of unstabilizedviscose to UV light leads to a loss in in strength ofabout 4%.3

Figure 13.2 Polyglycolic acid chemical structures.

Figure 13.3 Structures of several polyhydroxy-alkanoates.


Table 13.1 A List of Some Sustainable/Environmentally Friendly Polymer-Based Product Trade Nameand Trademarks2

Trade Mark Owner Material

Aqua-Novon Novon International Inc. (USA) PCL

BAK� Bayer AG Corporation (Germany) Polyester amide

BioBagInternational AS

Polargruppen (Norway) Mater-Bi�

Bioceta, Biocell,Biocelat

Mazzucchelli, S.p.A. (Italy) Cellulose acetate

Biofan Gunze (Japan) PHB/PHBV

Bio-Flex� Biotec GmbH (Germany) Starch

Biogreen Mitsubishi Gas Chemical Co. (Japan) PHB

Biomax� DuPont (USA) PBS-co-PBST

Biomer Biomer (Germany) Polyester, PHB

Bionolle 1000 Showa Highpolymer Co. (Japan) PBS

Bionolle 3000 Showa Highpolymer Co. (Japan) PBS-co-PBSA

Biopac Biopac Ltd (UK) Starch

BioPar� Biop AG Biopolymer GmbH (Germany) Starch, biodegradable synthetic polymer

Biophan� Trespaphan GmbH (Germany) PLA

Bioplast� Biotec GmbH (Germany) Starch, PLA, co-polyester

Biopol� Monsanto Co. (Italy)/Metabolix, Inc. (UK) PHB, PHV and PHAs

Biopur� Biotec GmbH (Germany) Starch

Bioska Plastiroll Oy (Finland) Starch/PVA

Bio-Solo Indaco Manufacturing Ltd (Canada) Starch, patented additives, PE

Biostarch� Biostarch (Australia) Maize starch

Bio-Stoll Stoll Papierfolien (Germany) Starch, LDPE/Ecostar, additive

Biotec� Bioplast GmbH (Germany) Thermoplastic starch (TPS�)

BioRez� Trans Furans Chemicals (Netherlands) Furan resin

Biothene� Biothene (UK) Biofuels from planted soy

CAPA� Solvay Polymers (Italy) PCL

CelGreen PH/P-CA Daicel Chemical Industries Ltd (Japan) PCL/cellulose acetate

CelloTherm UCB Films (UK) Regular cellulose (for microwave)

Chronopol Chronopol-Boulder, CO (USA) PLA

Clean Green StarchTech Inc, MN (USA) Starch-based biopolymers

Cohpol� VTT Chemical Technology (Finland) Starch ester

Cornpol� Japan Corn Starch (Japan) Modified starch

Corterra Shell Chemicals (USA/NL) PTT

Degra-Novon� Novon International Inc. (USA) Polyolefinþ additives

EarthShell� EarthShell Corp., MD (USA) Starch composite materials

Eastar Bio Eastman Chemical Company (USA) Co-polyester

(Continued )

13: SUSTAINABLE POLYMERS 373



ECM MasterbatchPellets

ECM Biofilms (USA) Additives for polyolefin products

Ecoflex� BASF Corporation (Germany) Poly(butyleneadipate)-co-PBAT

Eco-Flow National Starch & Chemical (USA) Starch-based biodegradable products

Eco-Foam� National Starch & Chemical Foamed starch

Eco-Lam National Starch & Chemical Starch, PET, PP

EcoPLA� Cargill Dow Polymers (USA) PLA

Ecoplast Groen Granulaat (Netherlands) Starch

EnPol IRe Chemical Co. Ltd (South Korea) PBS-co-PBSA

Envirofill� EnPac/DuPont/ConAgra (USA) Starch/PVA

Enviromold� Storopack Inc. (USA) Polystyrene expanded products

EnviroPlastic� Planet Polymer Technologies, Inc. (USA) Cellulose acetate

EverCorn� EverCorn, Inc. (USA) Starch

Fasal� Japan Corn Starch Co., Ltd. (Japan)Department Agrobiotechnology, Tulln,(Austria)

50% wood wastes

FLO-PAK BIO 8� FP International (USA) Starch (corn or wheat)

Gohsenol Nippon Gohsei (Japan) PVA

GreenFill Green Light Products Ltd (UK) Starch/PVA

Greenpol� SK Corporation (South Korea) Starch, aliphatic polyester

Hydrolene� Idroplax S.r.L. (Italy) PVA

LACEA� Mitsui Chemicals, Inc. (Japan) PLA from fermented glucose

Lacty Shimadzu Corp. (Japan) PLA

Lignopol Borregaard Deutschland GmbH Lignin

Loose Fill� STOROpack (Germany) EPS/starch

Lunare Nippon Shokubai Co., Ltd Polyethylenesuccinate/adipate

Mater-Bi� Novamont S.p.A. (Italy) Starch/cellulose derivative

Mazin Mazin International (USA) PLA

Mirel� Metabolix Inc. (USA) Corn sugar

NatureFlex� Innovia Films (UK) Regenerated cellulose film

NatureWorks� Cargill Co. (USA) PLA

Nodax� Procter & Gamble co. (USA) PHB-co-PHA

Novon� Ecostar GmbH (Germany) Starch

Paragon Avebe Bioplastic (Germany) Starch

Plantic� Plantic Technologies (Australia) Corn-starch materials

Poly-Novon� Novon International Starch additives

Polystarch Willow Ridge Plastics, Inc. (USA) Additives

POLYOX� Union Carbide Corporation (USA) Poly(ethylene oxide)

POVAL Kuraray Povol Co., Ltd (Japan) PVA


Manufacturers and trademarks: InnoviaCellophane�.

Applications and uses: Cellulosic film applica-tions include tapes and labels, photographic film,coatings for paper, glass, and plastic fibers forclothing.

Data for Cellophane/Viscose polymers are foundin Fig. 13.7.

13.2.2 Nitrocellulose

Nitrocellulose is made by treating cellulose withamixture of sulfuric and nitric acids. This changes thehydroxyl groups (eOH) on the cellulose to nitrogroups (eNO3) as shown if Fig. 13.8. Nitrocellulose,

also know as gun cotton and is the main ingredient ofsmokeless gunpowder, decomposes explosively. Inthe early twentieth century, it was found to make anexcellent film and paint. Nitrocellulose lacquer wasused as a finish on guitars and saxophones for most ofthe twentieth century and is still used on some currentapplications. Manufactured by (among others)DuPont, the paint was also used on automobilessharing the same color codes as many guitarsincluding Fender and Gibson brands. Nitrocelluloselacquer is also used as an aircraft dope, painted ontofabric-covered aircraft to tauten and provide protec-tion to the material. Its CAS number is 9004-70-0.

Nitrocellulose is not molded. It has been used incoatings; it was widely used as automotive paintin the 1930s. The early types of nitrocelluloseautomotive lacquers showed signs of deteriorationafter a few months’ exposure in Florida. 2-(20-Hydroxy-30,50-di-tert-butylphenyl)-5-chlorobenzo-triazole (example: Tinuvin 327) is highly effectivein stabilizing nitrocellulose coatings at a use levelrange of 0.5e2.0%, and can be used in combinationwith phenolic and phosphate antioxidants, as wellas (Hindered Amine Light Stabilizer), to optimizeperformance in outdoor applications.

Nitrocellulose is not usually used by itself for filmapplications, but more commonly is part of



Pullulan Hayashibara Biochemical (Japan) Starch

RenaturE� Storopack, Inc. (Germany) Starch

ReSource Bags� Ventus Kunststoff GmbH Mater-Bi

Sconacell� Buna SOW Leuna (Germany) Starch acetate, plasticizer

Sky-green Sunkyong Ltd (South Korea) Aliphatic-co-polyester

Solanyl� Rodenburg Biopolymers (Netherlands) Starch (from potato waste)

Sorona� DuPont Tate & Lyle (USA) PDO

SoyOyl� Urethane Soy Systems Co. Inc. (USA) Soy-based products

SPI-Tek Symphony Plastic Technologies Plc (UK) Additives

Supol� Supol GmbH (Germany) Starch plant oil and sugars

TONE� Union Carbide Corp. (USA) PCL

Trayforma Stora Enso Oyj (Finland) Cellulose, food tray

Vegemat� Vegeplast S.A.S. (France) Starch

Abbreviations: PHBV, polyhydoxybutyrate valerate; PBS-co-PBST, polybutylene succinate copolymer poly(butylenesuccinate-terephthalate); PBS-co-PBSA, polybutylene succinate copolymer polybutylene succynate adipate; PHV,polyhydroxyvalerate; LDPE, low-density polyethylene; PTT, polytrimethylene terephthalate; PBAT, poly(butyleneadipate-co-terephthalate); EPS, expanded polystyrene; PDO, poly(dioxanone).

Figure 13.4 Chemical structure of cellulose.


multilayered films structures, especially those basedon Cellophane�.Manufacturers and trade names: Innovia Films

Cellophane�.Applications and uses: Food wrap.

13.2.3 Cellulose Acetate

Cellulose acetate is the acetate ester of cellulose. Itis sometimes called acetylated cellulose or xylonite.

Its CAS number is 9004-35-7 and the approximatechemical structure is shown in Fig. 13.9.CA weathers well and is nonyellowing on long-

term exposure to the sun, making it useful asa coating for signs and decals. The transparency ofCA coatings and their ability to transmit sunlight,particularly beneficial ultraviolet rays, have led toextensive use of these film formers for coating wirescreening for greenhouse windows, poultry runsand similar structures. The good physical strength

Figure 13.5 UV degradation in cellulose.


of the coatings yields a tough, tear-resistantscreen.5

Manufacturers and trade names: CelaneseCellulose Acetate; Eastman Chemical CompanyTenite.

Applications and uses: Cellulose acetate is usedas a film base in photography, as a component insome adhesives, and as a frame material foreyeglasses; it is also used as a synthetic fiber and inthe manufacture of cigarette filters, found in screw-driver handles, ink pen reservoirs and X-ray films.

13.2.4 Cellulose Acetate Butyrate

Cellulose acetate butyrate (CAB) is a mixed esterof cellulose. CAB commonly known as butyrate, is

Figure 13.7 Effect of irradiation withUV light on the tensile strengthretention of unstabilized viscoserayon to that stabilized with thesulfuric acid ester of 4-fl-hydroxye-thylsulfonyl-2-aminoanisole.4

Figure 13.6 Conversion of raw cellulose to viscose.

Figure 13.8 Structure of nitrocellulose.


resistant to ultraviolet rays, has lower moistureabsorption than cellulose acetate and has extremelyhigh impact strength. Its CAS number is 9004-36-8and the approximate chemical structure is shown inFig. 13.10.Manufacturers and trade names: Eastman

Chemical Company Tenite; Uvex�; Excelon�,Spartech�.Applications and uses: Printing visual aids, page

protection and animation cells.Data for CAB polymers are found in Figs

13.11e13.13.

13.2.5 Ethyl Cellulose

Ethyl cellulose is similar in structure to celluloseand cellulose acetate but some of the hydroxyl

(eOH) functional groups are replaced on the cellu-lose by the ethoxy group (eOeCH2eCH3). Ethylcellulose has a CAS number of 9004-57-3 and itsstructure is shown in Fig. 13.14.Several phenolic stabilizers maybe be used with

ethyl cellulose.Manufacturers and trade names: Dow

Ethocel�, Ashland Aqualon�.Applications and uses: pharmaceutical applica-

tions, cosmetics, nail polish, vitamin coatings,printing inks, specialty coatings and food packaging.

13.3 Polycaprolactone

PCL is biodegradable polyester with a low meltingpoint of around 60 �C and a glass transitiontemperature of about �60 �C. PCL is prepared byring opening polymerization of 3-caprolactone usinga catalyst such as stannous octanoate. The structureof PCL is shown if Fig. 13.15.PCL is degraded by hydrolysis of its ester

linkages in physiological conditions (such as inthe human body) and has therefore receiveda great deal of attention for use as an implantablebiomaterial. In particular, it is especially inter-esting for the preparation of long-term implantabledevices. A variety of drugs have been encapsulatedwithin PCL beads for controlled release and tar-geted drug delivery. PCL is often mixed withstarch to obtain a good biodegradable material ata low price. Perstorp offer PCLs under the tradename CAPA�. Low molecular weight PCLs maybe added to other plastics to improve their weatherresistance.

Figure 13.9 Chemical structure of cellulose acetate.

Figure 13.10 Chemical structure of cellu-lose acetate butyrate.


Figure 13.11 Tensile strength atbreak after Arizona weathering forEastman Tenite� butyrate.2

Note: 3.2-mm (0.125-in.) thick speci-mens of an outdoor type of Tenite�

butyrate.

Figure 13.12 Elongation at breakafter Arizona weathering for black,colors and clear Eastman Tenite�

butyrate.2

Note: 3.2-mm (0.125-in.) thick speci-mens of an outdoor type of Tenite�

butyrate.

Figure 13.13 Impact strength afterweathering for black, colors andclear Eastman Tenite� butyrate.2

Note: 3.2-mm (0.125-in.) thick spec-imens of an outdoor type of Tenite�

butyrate; samples weathered ina vertical position facing due south.Testing as per ASTM D3029.


Manufacturers and trade names: PerstorpCAPA� (previously Solvay), Dow Chemical Tone(discontinued).Applications and uses: The mix of PCL and

starch has been successfully used for making trashbags in Korea (Yukong Company).

13.4 Poly(Lactic Acid)

PLA is derived from renewable resources, such ascornstarch or sugarcanes. PLA polymers areconsidered biodegradable and compostable. PLA isa thermoplastic, high-strength, high-modulus poly-mer that can be made from annually renewablesources to yield articles for use in either the industrialpackaging field or the biocompatible/bioabsorbablemedical device market. Bacterial fermentation isused to make lactic acid, which is then converted tothe lactide dimer to remove the water moleculewhich would otherwise limit the ability to make highmolecular weight polymer. The lactide dimer, afterthe water is removed, can be polymerized without theproduction of the water. This process is shown inFig. 13.16, and can proceed by two possible routes,the direct route and the lactide route. The PLA CASnumber is 9002-97-5.Manufacturers and trade names: FKur Bio-

Flex�, Cereplast Inc. Compostables�, MitsubishiChemical Fozeas�, NatureWorks LLC Ingeo�,Alcan Packaging Ceramis�-PLA.Applications and uses: Biomedical applications,

such as sutures, stents, dialysis media and drugdelivery devices. It is also being evaluated asa material for tissue engineering; loose-fill pack-aging, compost bags, food packaging, and disposabletableware. PLA can be in the form of fibers andnonwoven textiles; Potential uses: upholstery,disposable garments, awnings and feminine hygieneproducts.Data for PLA is shown in Figs 13.17e13.21.

Figure 13.14 Structure of ethyl cellulose.

Figure 13.15 Structure of polycaprolactone.

Figure13.16 Conversionof lacticacid to polylactic acid by tworoutes.


Figure 13.17 Tensile strength ofpoly(lactic acid) and polylactideduring a weather ability test (accel-erated test using a Weather-Ometer�).6

Figure 13.18 Tensile strength ofpoly(lactic acid) and polylactideduring an outdoor exposure test.6

Figure 13.19 Ball burst strengthvs. UV exposure time of IngeoPLA fabric.7

Note: Test method: ASTM D3787;ATTCC 16E light exposure.


References

1. Jain JP, Modi S, Domb a J, Kumar N. Role ofpolyanhydrides as localized drug carriers. JControlled Release: Off J Controlled Release Soc2005;103:541e63.

2. Chiellini E. Environmentally compatible foodpackaging. In: Environmentally compatible foodpackaging. Cambridge, UK: WoodheadPublishing Ltd; 2008. p. 371e95.

3. Compiled from various sources by ChiragPanchigar.

4. Boboev T, Makhkamov K. Stabilization ofviscose rayon exposed to photomechanicaldegradation. Mech Compos Mater; 1974:920e2.

5. Eastman� cellulose-based specialty polymers.Eastman Chemical Company; 2009.

6. Ajioka M, Enomoto K, Suzuki K, Yamaguchi a.The basic properties of poly(lactic acid) producedby the direct condensation polymerization oflactic acid. J Environ Polym Degrad 1995;3:225e34.

7. UV resistance, technical bulletin 370904. Ingeo,NatureWorks LLC; 2006.

Figure 13.20 Molecular weight lossvs. UV exposure time of Ingeo PLAfabric.7

Note: ATTCC (Association of TextileChemistsandColorists)TestMethod16 light exposure.

Figure 13.21 Color change vs. UVexposure time of Ingeo PLA fabric.7

Note: ATTCC (Association ofTextile Chemists and Colorists)Test Method 16 light exposure;HunterLab D65/10 � illuminator/observer.


Index

Note: Page numbers followed by “f” denote figures; “t” tables.

AABS. See Acrylonitrile-butadiene-styrene (ABS)

Accelerated indoor fluorescent light exposure, 73t

Accelerated outdoor tests, 31e32

EMMA�, 31e32, 32f

EMMAqua�, 32

ultra-accelerated exposure testing, 32, 32f

Acetal copolymer, chemical structure of, 282f

Acetal homopolymer, chemical structure of, 282f

Acetal polymers, 291

Acid scavenger, 26

Acrylic resins, 231

Acrylics, 217. See also Polyvinyls

Acrylonitrile-butadiene copolymers (NBR), 346e352, 351f

applications and uses, 352

manufacturers and trade names, 352

types of, 346e352Acrylonitrile-butadiene-styrene (ABS), 71f, 72f


physical properties of, 73t, 74f, 74t

property changes in, 73t

stabilization, 71

weathering properties, 71

Acrylonitrile-styrene-acrylate (ASA), 105

Alternating copolymer, 2

American Society for Testing and Materials (ASTM), 45

Amide-imide polymers, 148t

Amino acids, chemical structures of, 164f

Amorphous, 10

Amorphous nylon, 165, 166f

Amorphous polyamide, 165e166, 165f



Artificial accelerated tests, 32e40

carbon arc fade-meter�, 39

fluorescent/QUV, 33e38light sources, 32, 34t

SEPAP, 39e40

xenon arc, 33, 35f

ASA. See Acrylonitrile-styrene-acrylate (ASA)

Atmospheric pollutants, chemical effects of

nitrogen dioxide (NO2), 19

ozone, 18

photodegradation and photo oxidation, 19

sulfur dioxide (SO2), 18

BBASF Ultrason�, 279

4,4’-Bisphenol A Dianhydride (BPADA)

monomer, 146, 152f

photodegradation reactions of, 153f

Block copolymer, 2e3

Butyl rubber, 314e318, 318f, 319f, 320fapplications and uses, 318

manufacturers and trade names, 315e316

CCarbon arc, 33, 36f

Carbon black, 15

Cellophane�, 372e375, 377f


manufacturers and trademarks, 375

weathering, 372

Cellulose acetate, 376e377, 377f, 378f



Cellulose acetate butyrate, 377e378, 378f



Chlorobutyl rubber, 320e322, 320f, 322f, 323f



Coefficient of friction (COF), 13

Conventional aging, 29e31

Copolymerization, 292

Copolymers, 2e3. See also Polyoxymethylene (POM)

Crystalline, 10

Crystallinity, 49

DDaylight filters, 33

Degree of polymerization, 9

Degree of unsaturation (DoU), 4e5

Diacids, chemical structures of, 164f

Diamines, chemical structures of, 164f

Differential scanning calorimetry (DSC), 65

Dipole moment, 3

DMTA. See Dynamic mechanical thermal analysis (DMTA)

Drop dart impact test, 57e58

DuPont elastomer neoprene, 321

DuPont Kapton�, elongation of, 156f

DuPont Minlon�, 178t, 179t

exposure of, 178t

DuPont Tedlar�, 252

Dynamic mechanical thermal analysis (DMTA), 67, 67f

EECTFE. See Ethylene-chlorotrifluoroethylene (ECTFE)

Elastomers, 299

fluoroelastomers, 337e346, 345f, 345t

olefinic thermoplastic elastomers, 301e304

thermoplastic copolyester elastomers, 313e314, 313fTPU, 299e301, 300f, 301t

Elmendorf tear strength, 61, 61f

383

EMMA�. See Equatorial mount with mirrors for acceleration (EMMA�)

EMMAqua�. See Equatorial mount with mirrors for acceleration plus

water (EMMAqua�)

Epichlorohydrin rubber, 325e337, 342f, 343fapplications and uses, 337


EPS. See Expanded polystyrene (EPS)

Equatorial mount with mirrors for acceleration (EMMA�),

31e32, 32f

Equatorial mount with mirrors for acceleration plus water

(EMMAqua�), 32

ETFE. See Ethylene-tetrafluoroethylene copolymer (ETFE)

Ethyl cellulose, 378, 380f



Ethylene-chlorotrifluoroethylene (ECTFE), 262e266, 266fapplications and uses, 263e266


Ethylene-propylene rubbers, 324e325, 324t, 325t,340f, 341f, 342f


basic kinds of, 324


Ethylene-tetrafluoroethylene copolymer (ETFE), 258e262. See also

Polyethylene tetrafluoroethylene


mechanical properties of, 259e262, 263fEthylene-vinyl acetate copolymer, 357e361, 360f



stabilization, 361

weathering, 361

Ethylene-vinyl alcohol copolymer (EVOH), 217e218, 217f, 218t

defined, 217

desirable properties, 217e218


EVAL�, 218

EVOH. See Ethylene-vinyl alcohol copolymer (EVOH)

Expanded polystyrene (EPS), 72e74

FFalling dart impact strength, 60, 60f

Fade-meter�, 39

FEP. See Fluorinated ethylene propylene (FEP)

Ferro Corporation LPP30, 211f

Fiber-reinforced grades, 11e12

Flexural properties, 54

Fluorescent/QUV, 33e38Fluorinated ethylene propylene (FEP), 246, 246f



Fluoroelastomers, 337e346, 345f, 345tapplications, 346


types of, 337e345

Fluoropolymers

ECTFE, 262e266, 266f

ETFE, 258e262

FEP, 246, 246f

PCTFE, 252e256, 257f, 258fPFA, 247e250, 250f, 250t

PTFE, 243e245, 244f, 246f

PVDF, 256e258, 258fPVF, 250e252, 252f

Free-Falling Dart Method, 57e58, 58f

GGardner impact strength, 60, 60f

General purpose polystyrene (GPPS), 87t, 88f, 93

Generalized polyamide reaction, 163, 164f

Glass transition temperature

estimating, mechanical methods of, 66e67

estimating, thermal methods of, 67e69

thermal mechanical analysis, 67

Gloss measurement, 45

Graft copolymer, 2e3

Grilamid� TR55, 165, 165f, 177f, 178f

Weather-Ometer� exposure of, 166, 166f

HHALS. See Hindered amine light stabilizers (HALS)

Haze measurement, 45e46

Heat distortion temperature (HDT), 63

High-density polyethylene (HDPE), 193, 195

High-gloss Tedlar�, 252

High-impact polystyrene (HIPS), 3, 74, 93e95

High molecular weight (HMW), 272

High-performance polyamide. See polyphthalamide

High-speed puncture test, 54e57, 58f

High-temperature/high-performance polymers

PAEK, 271e272, 271f

parylene, 279e283

PES, 276e279, 280t, 281f, 282f

polyoxymethylene copolymer, 282f, 284e295POM, 282f, 283e285

PPO, 291f, 292f, 293t, 295e296

PPS, 272e274, 273f, 275t

PPSU, 275e276, 279fPSU, 274e275, 276f

Hindered amine light stabilizers (HALS), 22e23, 163

Hiosynergist inorganic screener, 24

Homopolymer, 245. See also Polyoxymethylene (POM)

IIndoor and interior exposures, 28e29

Ionomers, 233e238, 237fdefined, 233

ethylene acrylic acid copolymer, 237f


UV protection in, 236e238


Isomers, 5e7

geometric isomers, 6, 6f

stereoisomers, 6e7

structural isomers, 5e6, 6f

LLCPs. See Liquid crystalline polymers (LCPs)

Light sources, artificial accelerated tests, 32, 34t

Linear low-density polyethylene (LLDPE), 193, 195

Liquid crystalline polymers (LCPs), 107e108applications and uses, 108



Low-density polyethylene (LDPE), 193, 195

MMechanical testing, 47e62

flexural properties, 54

gardner and falling dart impact strength, 60

izod impact strength and charpy impact strength, 58e59

384 INDEX

plastics materials, rigidity of, 48e49

puncture and impact, 54e58

shear properties, 49e51

tear properties, 60e62

tensile properties, 47e48

Medium-density polyethylene, 193

Melt flow index, 63

Mercury vapor, 32e33Metal halide lamps, 33, 35f

Molecule affects, polarity of, 4

Monomers, chemical structures of, 121f, 155, 155f

Multiphase polymer blends, 11

NNatural rubber, 346, 348f


NBR. See Acrylonitrile-butadiene copolymers (NBR)

Nitrocellulose, 375e376, 377f



Nitrogen dioxide (NO2), 19

Nylon 6. See Polyamide 6




OOlefinic thermoplastic elastomers, 301e304



Optical brighteners, 163

Outdoor testing, 29

Outdoor weathering

antioxidants effects on, 209t

glass-reinforced polypropylene, 209t

in Puerto Rico of Polypropylene, 210t

time vs. yellowness index, 75f

Ozone testing, 40

PPAEK. See Polyaryletherketone (PAEK)

Parylene, 279e283

Parylene polymers, 279e283, 282f


results, 283

weathering resistance, 282e283

PBT. See Polybutylene terephthalate (PBT)

PCTFE. See Polychlorotrifluoroethylene (PCTFE)

PES. See Polyethersulfone (PES)

PEN. See Polyethylene naphthalate (PEN)

Perfluoro alkoxy (PFA), 247e250, 250f, 250t



PET. See Polyethylene terephthalate (PET)

PFA. See Perfluoro alkoxy (PFA)

Phase-separated mixtures, 11

Phenolic antioxidants, 23, 163

Phosphites, 24

Phosphonites, 24

Photodegradation, radicals, reactions of, 19, 20t

PLA. See Poly(lactic acid) (PLA)

Plastics

compositions

antiblock additives, 14

antistatic additives, 16

catalysts, 14

combustion modifiers, 12

coupling agents, 15

dyes and mica, 15

fillers/reinforcement and composites, 11e12

fire/flame retardants and smoke suppressants, 12

impact modifiers and tougheners, 14

optical brighteners, 15

pigments and extenders, 15

plasticizers, 15

release agents, 13

slip additives/internal lubricants, 13e14thermal stabilizers, 15e16

UV/radiation stabilizers, 14

defined, 1

Plastics materials, weathering on, 17

atmospheric pollutants, chemical effects of, 18e19

physical processes of, 17

testing, 28e40UV stabilization, mechanisms of, 19e21

Plastic properties

appearance of

color, 43e45gloss measurement, 45

haze measurement, 45e46

yellowness index, 46e47

mechanical testing, 47e62flexural properties, 54

gardner and falling dart impact strength, 60, 60f

izod impact strength and charpy impact strength,

58e59, 59f, 60f

plastics materials, rigidity of, 48e49

puncture and impact, 54e58

shear properties, 49e51tear properties, 60e62

tensile properties, 47e48

thermal property testing of, 62e69

glass transition temperature, 65e69heat deflection temperature, 63

melt flow index, 63

melting point, 65

vicat softening temperature, 63

Plastics Web�, 1

PMMA. See Polymethyl methacrylate (PMMA)

Polar bond, 3

Polyacrylics, 220e233, 231f



PMMA, 220e231stabilization, 233

weathering, 232

Polyamide 6, 169e170, 169f





weathering resistance, 176

Polyamide 12, 167f, 176e177, 177f, 178f


weathering resistance, 177


characteristics of, 177e178



Polyamide copolymers. See Amorphous polyamide

Polyamide-imide, 145e146, 145f, 146f

INDEX 385




Polyamides nylons

amorphous polyamide, 165e166, 165f

polyamide 6, 169e170, 169f

polyamide 11, 170e176, 176f

polyamide 12, 167f, 176e177, 177f, 178fpolyamide 66, 177e178, 178f

polyarylamide, 178e181, 184f

polyphthalamide/high-performance polyamide, 188f, 190

stabilization, 163


Polyarylamide, 178e181, 184f



Polyaryletherketone (PAEK), 271e272, 271f

commercial plastics, 271



Polybutylene terephthalate (PBT), 108e112, 110f



stabilization, 110


Polycaprolactone, 378e380, 380f



Polycarbonate, 112e134, 121f


optical brightener, 131

phenolic antioxidant, 131

phosphite, 131

photo-Fries rearrangement in, 121f

polycarbonate blends, 131e134

stabilization, 131


Polycarbonate blends

stabilization, 134


Polychlorotrifluoroethylene (PCTFE), 252e256, 257f, 258f


Polydispersity (PDI), 8e9

Polyesters

chemical structure of, 107f

crystalline polymer, 109f

LCPs, 107e108, 109f

PBT, 108e112, 110f

PEN, 141f, 142

PET, 131f, 134e142

photolysis of, 108f

polycarbonate, 112e134, 121f

Polyetherimide, 146, 150f, 151f, 152f



stabilization, 146


Polyethersulfone (PES), 276e279, 280t, 281f, 282f



Polyethylene, 193e207, 194f

Polyethylene naphthalate (PEN), 141f, 142



weathering, 142

Polyethylene terephthalate (PET), 131f, 134e142



stabilization, 141

weathering properties, 134e141Polyethylene tetrafluoroethylene, 258

Polyhydroxyalkanoates (PHAs), 372, 372f

Polyimides, 155e156, 155f




photochemical oxidation of, 155f

polyamide-imide, 145e146polyetherimide, 146, 150f, 151f, 152f


Poly(lactic acid) (PLA), 380, 380f



Polymer

classifications

crystalline vs amorphous, 10

molecular weight, 8e9

thermosets vs thermoplastics, 9e10

inter- and intramolecular attractions in, 7e8chain entanglement, 8

hydrogen bonding, 7

van der waals forces, 8

polarities, qualitative ranking of, 4f

Polymer degradation cycle, 19e20, 20f

Polymerization

addition, 1e2, 2fcondensation, 2, 2f

Polymethyl methacrylate (PMMA), 220e231

Poly-4-methyl-1-pentene



Polyolefins

HDPE, 195

LDPE, 195

LLDPE, 195

monomers, chemical structures of, 193f

poly-4-methyl-1-pentene, 208e214

polyethylene, 193e207, 194fpolypropylene, 207e208

stabilization, 194

UHMWPE, 195e207weathering, 194

Polyoxymethylene (POM), 282f, 283e285

Polyoxymethylene copolymer, 282f, 284e295



properties of, 292

stabilization, 293

weathering, 292

Polyphenylene oxide (PPO), 67, 291f, 292f, 293t, 295e296

Noryl� resins, 296

stabilization, 296

weathering, 295

Polyphenylene sulfide (PPS), 272e274, 273f, 275t


stabilization, 273

weathering, 273

Polyphenylsulfone (PPSU), 275e276, 279f



properties of, 275e276

Polyphthalamide (PPA), 188f, 190

386 INDEX


characteristics of, 190


Polypropylene, 207e208homopolymers, 207

impact copolymers, 208

random copolymers, 207

stabilization, 208

weathering, 208

Polystyrene


stabilization, 86

structure of, 86f


Polysulfide rubber, 361e364, 363f

Polysulfone (PSU), 276f


weathering, 274

Polytetrafluoroethylene (PTFE), 13, 243e245, 244f, 246fPolyvinyl chloride (PVC), 217e220, 219f, 220f

applications and uses, 219e220

dehydrochlorination of, 219f

manufacturing and trade names, 219

radical generation in, 220f

stabilization, 219e220

weathering, 219

Polyvinyl fluoride (PVF), 250e252, 252f

general description, 250


Polyvinylidene fluoride (PVDF), 256e258, 258f

key attributes of, 258



Polyvinyls

EVOH, 217e218, 217f, 218t

ionomers, 233e238, 237f

polyacrylics, 220e233, 231f

polyvinyl chloride, 218e220, 219f, 220f

POM. See Polyoxymethylene (POM)

PPO. See Polyphenylene oxide (PPO)

PPS. See Polyphenylene sulfide (PPS)

PPSU. See Polyphenylsulfone (PPSU)

PSU. See Polysulfone (PSU)

PTFE. See Polytetrafluoroethylene (PTFE)

Punch-type shear tool, 51

Puncture properties, 54e58

drop dart impact test, 57e58

high-speed puncture test, 54e57, 58f

PVC. See Polyvinyl chloride (PVC)

PVDF. See Polyvinylidene fluoride (PVDF)

PVF. See Polyvinyl fluoride (PVF)

RRandom copolymer, 2e3

Rubbers, 299

butyl rubber, 314e318, 318f, 319f, 320f

chlorobutyl rubber, 320e322, 320f, 322f, 323f

epichlorohydrin rubber, 325e337, 342f, 343f

ethylene-propylene rubbers, 324e325, 324t, 325t,

340f, 341f, 342f

ethylene-vinyl acetate copolymer, 357e361, 360f

natural rubber, 346, 348f

NBR, 346e352, 351f

polysulfide rubber, 361e364, 363fSBR, 352e357, 357f

SSabic Innovative Polymers Ultem�, 154f, 155, 155f

Salt solution, 31, 31f

Semicrystalline polyamides, properties of, 176e177

SEPAP, 39e40Shear modulus, 49

Shear properties, 49e51

Solar, and artificial light exposure, 33, 35t

Spray, conventional aging with, 31

Standard elastomer tests, 47, 50t

Standard electrical tests, 47, 51t

Standard hardness tests, 47, 50t

Standard impact tests, 47, 50t

Standard mechanical tests, 47, 49t

Standard thermal tests, 47, 51t

Statistical copolymer. See Random copolymer

Stress, vs. strain behaviors, 54f

Styrene acrylonitrile (SAN) copolymer, 93f, 103e105



stabilization, 105

weathering properties, 104e105

Styrene-butadiene rubber (SBR), 352e357, 357f



Styrenic plastics

ABS copolymer, 71e72

acrylonitrile-styrene-acrylate, 105

polystyrene, 72e103

SAN copolymer, 103e105

Styrosun�, 93e94Sustainable polymers

cellulose-based materials, 372e378, 375f, 376f

Cellophane�, 372e375, 377f

cellulose acetate, 376e377, 377f, 378fcellulose acetate butyrate, 377e378, 378f

ethyl cellulose, 378, 380f

nitrocellulose, 375e376, 377f

PLA, 380, 380f

polycaprolactone, 378e380, 380f

Syndiotactic polystyrene (SPS), 95e103

TTear properties

Elmendorf tear strength, 61, 61f

toughness, 62

trouser tear resistance, 61

Tedlar�, 252

Teflon�, 245

Tensile properties, 47e48Testing

accelerated outdoor tests, 31e32

artificial accelerated tests, 32e40

conventional aging, 29e31indoor and interior exposures, 28e29

outdoor testing, 29

ozone testing, 40

spray, conventional aging with, 31

Thermal mechanical analysis (TMA), 67, 68f

Thermal property testing

heat deflection temperature, 63

melt flow index, 63

vicat softening temperature, 63

Thermoplastic copolyester elastomers, 313e314, 313f


INDEX 387


Thermoplastic polyurethane elastomers (TPU), 299e301, 300f, 301t

aliphatic, 300

aromatics, 300

characteristic features, 300

polycaprolactone, 300

polyester, 299

polyether, 300

UV radiation resistance, 301

Thermoplastics, 9e10

Thermosets, 9e10

Ticona Celanex�, 111t

Ticona Vectra�

artificial weathering for, 110t


xenon arc accelerated weathering for, 110t

TIPU. See Thermoplastic polyurethane elastomers (TPU)

Titanium dioxide, 15, 219

Tortuous path effect, 12

Tristimulus coefficients, 46, 46t

UUltrahigh molecular weight polyethylene (UHMWPE), 193

Ultra low-density polyethylene, 193

Ultraviolet (UV)

light, 1

absorber, 22, 163

Ultraviolet (UV) stabilization

acid scavenger, 26

hindered amine stabilizers, 22e23

inorganic screeners, 24

mechanisms of, 19e21absorption/reflection and refraction, 20e21

phenolic antioxidants, 23

phosphites and phosphonites, 24

quencher, 28

synergistic mixtures of, 28

thiosynergists, 26

UV absorbers, 22

Ultraviolet (UV) stabilizers, 21e28. See also Ultraviolet (UV)

stabilization

Unsaturation, 4e5

VVery low-density polyethylene, 193

Vicat softening temperature, 63

WWeather-Ometer�, 146, 149f

XXenon arc, 33, 35f, 146, 153f

YYellowness index, 46e47, 89f, 146, 154f

388 INDEX

Documents

The Effect of UV Light and Weather on Plastics and Elastomers