Commodity Thermoplastics

7/30/2019 Commodity Thermoplastics

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Commodity

Thermoplastics

Polymer Technology


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Thermoplastics What are Thermoplastics?

Classification of Thermoplastics Commodity Thermoplastics

Engineering Thermoplastics


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What are Thermoplastics? Linear polymers whose molecules are not

linked by covalent bonds and can slide past

each other on the application of heat andpressure.

Polymers that soften on heating and can be

processed into a desired form by a varietyof fabrication methods.

Polymers are often soluble and can be

manipulated as solutions.


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Classification of Thermoplastics Commodity Thermoplastics

High Volume Usage

Low Cost

Engineering Thermoplastics

Low Volume Usage High Cost

Better Properties


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Commodity Thermoplastics

Polyolefins

Polyethylene (PE)

Polypropylene (PP)

Vinyl Polymers

Polyvinyl Chloride (PVC) Polystyrene (PS)

Polymethyl Methacrylate (PMMA)


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Polyolefins Polyethylene (PE)

Low Density Polyethylene (LDPE)

High Density Polyethylene (HDPE)

Linear Low Density Polyethylene (LLDPE)

Very Low Density Polyethylene (VLDPE)

High Molecular Weight High density Polyethylene (HMW-HDPE) Ultra High Molecular Weight Polyethylene (UHMWPE)

Polypropylene (PP)


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Polyethylene or polythene is the mostcommon and widely used plasticworldwide.

Polyethylene is a thermoplastic polymerconsisting of long hydrocarbon chains.

Annual production is approximately 80million metric tons with primary use inpackaging.

Polyethylene (PE)


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PE first commercially produced by British Company ImperialChemical Industries (ICI) in 1939.

Preparation required high temperatures up to 200o C and high

pressures up to 2000 atm resulting in a material with shorter,branched chains, which was waxy and easily deformed.

In 1953 Ziegler (Germany), Phillips Petroleum Company (USA) andStandard Oil (USA) almost simultaneously prepared high molecular

weight PE at low temperatures and low pressures which was linear,hard and rigid.

Giulio Natta extended Zieglers research, eventually showing how thegeometry of polyethylene could be controlled by certain catalysts.

New material became known as HDPE and older material as LDPE.

Development


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Chemical Structure PE is an addition polymer made by the

polymerisation of ethylene monomer, C2H4.

Different classes of PE are available, withthe general chemical formula (C2H4)n


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Classification Low Density Polyethylene (LDPE)

High Density Polyethylene (HDPE)

Linear Low Density Polyethylene (LLDPE)

Very Low Density Polyethylene (VLDPE)

High Molecular Weight High DensityPolyethylene (HMW-HDPE)

Ultra High Molecular Weight Polyethylene

(UHMWPE)


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Properties

Properties dependent on: Chemical Structure

Molecular Weight Chemical Resistance

Excellent chemical resistance

Resistant to strong acids or strong bases

Resistant to gentle oxidants and reducing agents. Solubility

Crystalline samples do not dissolve at room temperature.

Soluble at elevated temperatures in aromatic hydrocarbons(toluene or xylene), or in chlorinated solvents (tricholoroethane ortrichlorobenzene).


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LDPE: Physical Properties

_____________________________________________________________________

Property LDPE_____________________________________________________________________

Specific Gravity 0.91 - 0.93Crystallinity, % 50 - 70

Melt Temperature, oC 98 - 120

Tensile Strength, MPa 4.1 - 16

Tensile Modulus, GPa 0.10 - 0.26

Elongation-to-Break, % 90 - 800Impact Strength No Break

Notched Izod, J m-1

Heat Deflection 38 - 49oC, at 455 kPa (66 psi)

_____________________________________________________________________


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HDPE: Preparation

Ziegler Process Pressures of 2 4 atm and temperatures of 50 75 oC.

Polymerisation in the presence of Ziegler Natta catalysts.

Phillips Process Pressures of 30 - 40 atm and temperatures of 90 160 oC.

Polymerisation in the presence of Chromium Oxide catalysts.

Standard Oil Process Pressures of 40 100 atm and temperatures of 200 - 300 oC.

Polymerisation in the presence of metal oxide catalysts

Union Carbide Process

Pressures of 7

20 atm and temperatures of ca. 100o

C. Polymerisation in the presence of metal oxide catalysts.


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Physical Properties Translucent material

Reduced branching results in a more closelypacked structure, more crystalline, higherdensity.

Chemical Resistance Chemical resistance slightly higher than that of

LDPE.

Resists alcohols, acids, bases, esters, andaldehydes.

HDPE: Properties


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Physical Properties

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Property LDPE HDPE_____________________________________________________________________

Specific Gravity 0.91 - 0.93 0.94 - 0.97Crystallinity, % 50 - 70 80 - 95

Melt Temperature, oC 98 - 120 127 - 125

Tensile Strength, MPa 4.1 - 16 21 - 38

Tensile Modulus, GPa 0.10 - 0.26 0.41 - 1.24

Elongation-to-Break, % 90 - 800 20 - 130Impact Strength No Break 27 - 1068

Notched Izod, J m-1

Heat Deflection 38 - 49 60 - 88oC, at 455 kPa (66 psi)

_____________________________________________________________________


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Applications

Packaging

Film

Pipes Milk bottles, toys, beer crate, food packaging, Shrink

wrap, squeeze tubes, disposable clothing, plastic bags,

paper coatings, cable insulation, artificial joints, Fibers - low cost ropes and packing tape reinforcement.


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LLDPE

Preparation Produced through catalyst selection & regulation of reactor conditions

Contains little if any branching Densities range between 0.916 and 0.930

Properties Good Flex Life

Low Warpage

Improved Stress-Crack Resistance

Applications Films for ice, trash, garment, and produce bags


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VLDPE

Preparation

Produced through catalyst selection and regulation of

reactor conditions Densities range between 0.890 and 0.915

Applications

Disposable gloves, shrink packages, vacuum cleanerhoses, tuning, bottles, shrink wrap, diaper film liners, and

other health care products.


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HMW-HDPE


Densities are 0.941 or greater

MW range from 200,000 to 500,000

Properties

Improved toughness, chemical resistance, impact strength, and highabrasion resistance, high viscosities.

Applications Trash liners, grocery bags, industrial pipe, gas tanks, and shipping

containers.


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UHMW-HDPE


Densities are 0.960 or greater MW range from 300,000,000 to 600,000,000

Properties Improved high wear resistance, chemical inertness, and low

coefficient of friction.

High viscosities result in material not flowing or melting.

Applications

Pump parts, seals, surgical implants, pen tips, and butcher-blockcuttin surfaces.


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Polypropylene (PP)

Polypropylene (PP), also known as polypropene,is a thermoplastic polymer used in a wide variety

of applications. PP is an addition polymer made from the

monomer propylene, it is rugged and unusuallyresistant to many chemical solvents, bases and

acids.

In 2008, the global market for polypropylene hada volume of 45.1 million metric tonnes.


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Development

Propylene was first polymerized to a crystallineisotactic polymer by Giulio Natta in 1954.

This pioneering discovery led to large-scalecommercial production of isotactic PP in 1957.

Syndiotactic polypropylene was also firstsynthesized by Natta and his co-workers.

PP is second most important plastic with revenuesexpected to exceed US$145 billion by 2019.

The demand for PP was growing at a rate of 4.4%

per year between 2004 and 2012.


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Chemical Structure

PP is an addition polymer made by thepolymerisation of propylene monomer,

C3H6.

PP has the chemical formula (C3H6)n


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Preparation

Polypropylene produced with low pressureprocess (Ziegler)

Polypropylene produced with linear chains Polypropylene is similar in manufacturing

method and in properties to PE

Commercial PP is 90% to 95% isotactic. Isotactic PP - CH3 group on one side of the

polymer chain.


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Classification

The most important way to classifypolypropylene is based on its chemical

structure:Atactic

Isotactic

Syndiotactic


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Isotactic PP

Most commercially important in comparison with theatactic and syndiotactic forms.

Isotactic propylene has the most stereo-regular structureof polypropylenes and therefore achieves a high degreeof crystallinity.

Mechanical properties and the processability ofpolypropylene are highly determined by the level ofisotacticity and crystallinity.

Isotactic PP


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Atactic PP

The atactic polymer is sticky, amorphous and has a lowmolecular weight.

These polymers provide the same effect as a plasticizer,reducing the crystallinity of polypropylene.

A small amount of atactic polymer at the end of thepolymer can be used to provide certain mechanicalproperties such as performance at lower temperatures,elongation, and optical and processable properties.


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Syndiotactic PP

The syndiotactic polypropylene has recentlybeen developed commercially, with the methyl

radicals staggered along the chain in an orderlymanner stereochemically.

Syndiotactic PP


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Physical Properties

_____________________________________________________________________

Property PP_____________________________________________________________________

Specific Gravity 0.90 - 0.91Crystallinity, % 82

Melt Temperature, oC 165 - 171

Tensile Strength, MPa 31 - 41

Tensile Modulus, GPa 1.10 - 1.55

Elongation-to-break, % 100 - 600Impact Strength 21 - 53

Notched Izod, J m-1

Heat Deflection 225 - 250oC, at 455 kPa (66 psi)

_____________________________________________________________________


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Properties of Commodity Polyolefins

_____________________________________________________________________

Property LDPE HDPE PP_____________________________________________________________________

Specific Gravity 0.91 - 0.93 0.94 - 0.97 0.90 - 0.91Crystallinity, % 50 - 70 80 - 95 82

Melt Temperature, oC 98 - 120 127 - 125 165 - 171

Tensile Strength, MPa 4.1 - 16 21 - 38 31 - 41

Tensile Modulus, GPa 0.10 - 0.26 0.41 - 1.24 1.10 - 1.55

Elongation-to-Break, % 90 - 800 20 - 130 100 - 600Impact Strength No Break 27 - 1068 21 - 53

Notched Izod, J m-1

Heat Deflection 38 - 49 60 - 88 225 - 250oC, at 455 kPa (66 psi)

_____________________________________________________________________


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Properties

Light and ductile but it has low strength.

It is more rigid than PE and can be used at highertemperatures.

The properties of PP are similar to those of HDPE but it isstiffer and melts at a higher temperature (165 - 170 C).

Stiffness and strength can be improved further byreinforcing with glass, chalk or talc.

When drawn to fibre PP has exceptional strength andresilience; this, together with its resistance to water, makesit attractive for ropes and fabric.

It is more easily moulded than PE, has good transparency

and can accept a wider, more vivid range of colours.


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Advantages of PP

Low Cost

Excellent Flexural Strength

Good Impact Strength Low Coefficient of Friction

Excellent Electrical Insulation

Good Fatigue Resistance Excellent Moisture Resistance

Service Temperature to 126 oC

Very Good Chemical Resistance


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Disadvantages of PP

High Thermal Expansion

UV Degradation

Poor Weathering Resistance

Poor Resistance to Chlorinated Solvents &Aromatics

Difficulty to Bond or Paint

Oxidizes Readily

Flammable


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Applications

Packaging

Clothing

Medical Applications Ropes, general polymer engineering, automobile air

ducting, parcel shelving and air-cleaners, gardenfurniture, washing machine tank, wet-cell battery

cases, pipes and pipe fittings, beer bottle crates,chair shells, capacitor dielectrics, cable insulation,kitchen kettles, car bumpers, shatter proof glasses,crates, suitcases, artificial turf, thermal underwear.


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Vinyl Polymers

Polystyrene (PS)

Poly(Vinyl Chloride) (PVC) Poly(Methyl Methacrylate) (PMMA)


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Polystyrene (PS)

Polystyrene is a synthetic aromatic polymermade from the monomer styrene, a liquid

petrochemical. Polystyrene can be rigid or foamed.

General purpose polystyrene is clear, hard

and brittle. PS is a very inexpensive resin per unit

weight.


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Chemical Structure

PS is an addition polymer made by thepolymerisation of styrene monomer, C8H8.

PS has the chemical formula (C8H8)n
http://en.wikipedia.org/wiki/File:Polystyrene_formation.PNG


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Properties

PS does not crystallize, and the resultingmaterial is transparent with a high

refractive index. The benzene ring absorbs UV light,

exploited in the PS screening of

fluorescent lights but causes the polymerto discolor in sunlight.

Excellent electrical resistance and

dielectric strength, exploited in switchgear.


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Properties of Styrenic Polymers

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Property GPPS HIPS ABS_____________________________________________________________________

Specific Gravity 1.04

1.05 1.03

1.06 1.03

1.58Tensile Strength, MPa 36.6 54.5 22.1 33.8 41.4 51.7

Tensile Modulus, GPa 2.41 3.38 1.79 3.24 2.07 2.76

Elongation-to-Break, % 1 - 2 13 - 50 5 - 25

Impact Strength 13.3 21.4 26.7 - 587 160 - 320

Notched Izod, J m-1

Heat Deflection 75 - 100 75 - 95 102 - 107oC, at 455 kPa (66 psi)

_____________________________________________________________________


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Applications

Packaging

Construction

Medical Applications Art and Craft

Toys; light diffusers; beakers; cutlery;

general household appliances;video/audio cassette cases; electronichousings; refrigerator liners.


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Polyvinyl Chloride (PVC)

Polyvinyl chloride is the third-most widely producedplastic after polyethylene and polypropylene.

PVC is used in construction because it is more effectivethan traditional materials such as copper, iron or woodin pipe and profile applications.

It can be made softer and more flexible by the additionof plasticisers, the most widely used being phthalates.

In this form, it is also used in clothing and upholstery,electrical cable insulation, inflatable products and manyapplications in which it replaces rubber.


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Chemical Structure

Polyvinyl Chloride is an addition polymermade by the polymerisation of vinyl chloride

monomer, C2H3Cl. Polyvinyl Chloride has the chemical formula:

(CH2CHCl)n


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Physical Properties

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Property Rigid Flexible_____________________________________________________________________

Specific Gravity 1.03 1.58 1.16 1.35Tensile Strength, MPa 41.4 51.7 22.1 33.8Tensile Modulus, GPa 2.41 - 4.14 1.79 3.24

Elongation-to-Break, % 2 - 80 13 - 50

Impact Strength 21.4 - 1068 26.7 - 587

Notched Izod, J m-1

Heat Deflection 57 - 82 75 - 95oC, at 455 kPa (66 psi)

_____________________________________________________________________


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Properties

Pure PVC is a white, brittle solid.

PVC is insoluble in alcohol, but slightly

soluble in tetrahydrofuran. Excellent resistance to acids and bases

Good barrier properties to atmospheric

gasses. Poor resistance to some solvents.


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Applications

uPVC

Pipes, Fittings, Profiles, Road Signs.

Window and Cladding, Door Frames.

Garden hoses, vinyl flooring, vinylrecords, dolls, medical tubes.

pPVC

Artificial leather, wire insulation, film.

Sheet, fabric, car upholstery.


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Applications


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Polymethyl Methacrylate (PMMA)

PMMA is a transparent thermoplastic,often used as a lightweight or shatter-

resistant alternative to glass.

Although it is not technically a type ofglass, the substance has sometimes

historically been called acrylic glass.


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Development

The first acrylic acid was made in 1843 and methacrylic acid,derived from acrylic acid, was formulated in 1865.

The reaction between methacrylic acid and methanol results in

the ester methyl methacrylate. German chemist Wilhelm Rudolph Fittig and co-workers in 1877

polymerised methyl methacrylate into polymethyl methacrylate.

In 1933 German chemist, Otto Rhm, patented and registeredthe brand name PLEXIGLAS.

In 1936 the first commercially viable production of acrylic safetyglass began by ICI Acrylics.

During World War II acrylic glass was used for submarineperiscopes, windshields, canopies, and gun turrets for airplanes


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Chemical Structure

PMMA is an addition polymer made by thepolymerisation of methyl methacrylate

monomer, C5O2H8.

PMMA has the chemical formula (C5O2H8)n


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Preparation

PMMA is routinely produced by emulsion,solution and bulk polymerisation.

Generally, radical initiation is used,including living polymerisation, but anionicpolymerization of PMMA can also be

performed. PMMA produced by radical polymerisation

is atactic and completely amorphous.


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Properties

PMMA is a strong and lightweight material.

It has a density of 1.17 1.20 g/cm3, which is less thanhalf that of glass.

Good impact strength, higher than both glass andpolystyrene.

PMMA swells and dissolves in many organic solvents.

Poor resistance to many other chemicals on account of

its easily hydrolysed ester groups.

Environmental stability is superior to most other plasticssuch as polystyrene and polyethylene, and PMMA istherefore often the material of choice for outdoor

applications.


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Applications

Automotive Industry

Transparent Glass Substitute Electrical Applications

Medical Applications

Light Fixtures, Car Lamps, Signs, Counter tops,Decorative pieces, Floor waxes, Paint, Fingernailpolishes, Contact lenses, Glasses


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Applications


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Commodity Thermoplastics