Commodity Thermoplastics_ LDPE, HDPE, PP, PVC, PS

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Commodity Thermoplastics_ LDPE, HDPE, PP, PVC, PS

Professor Joe GreeneCSU, CHICO

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Polyolefin Definition • Olefins: Unsaturated, aliphatic hydrocarbons made from ethylene gas• Ethylene is produced by cracking higher hydrocarbons of natural gas

or petroleum• Olefin means oil forming• Historically given to ethylene because oil was formed when ethylene

was treated with Cl.• Now applies to all hydrocarbons with linear C::C double bonds (not

aromatic C::C double bonds)• Polyethylene discovered around 1900, though using an expensive

process• LDPE commercialized in 1939 • HDPE commercialized in 1957

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Principal Olefin Monomers

• Ethylene Propylene

• Butene-1 4-Methylpentene

C C

H H

H H

C C

C2H5 H

H H

C C

CH3 H

H H

C C

C5H6 H

H H

CH3

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Several Olefin Polymers

• Poly Ethylene Poly Propylene

• PolyisoButene PolyMethylpentene

C C

C2H5 H

H H

n

C C

C5H6 H

H H

CH3

n

C C

H H

H H

n

C C

CH3 H

H H

n

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Polymers Derived from Ethylene Monomer

X Position Material Name AbbreviationH Polyethylene PECl Polyvinyl chloride PVCMethyl group Polypropylene PPBenzene ring Polystyrene PSCN Polyacrylonitrile PANOOCCH3 Polyvinyl acetate PvaCOH Polyvinyl alcohol PVACOOCH3 Polymethyl acrylate PMAF Polyvinyl fluoride PVF

Note:Methyl Group is:

|H – C – H | H

Benzene ring is:

X Position Y Position Material Name AbbreviationF F Polyvinylidene fluoride PVDFCl Cl Polyvinyl dichloride PVDCCH3 (Methyl group) CH3 Polyisobutylene PBCOOCH3 CH3 Polymethyl methacrylate PMMA

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Addition Polymerization of PE• Polyethylene produced with low (Ziegler) or high pressure (ICI) • Polyethylene produced with linear or branched chains

C C

H H

H H

n

C C

H H

H H

C C

H H

H H

C C

H H

H H

C C

H H

H H

OR

C C

H H

H H

n

C C

H H

H H

C C

H

H H

C C

H H

H H

C C

H H

H HC

CHH

HH

n

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Mechanical Properties of Polyethylene• Type 1: (Branched) Low Density of 0.910 - 0.925 g/cc• Type 2: Medium Density of 0.926 - 0.940 g/cc• Type 3: High Density of 0.941 - 0.959 g/cc• Type 4: (Linear) High Density to ultra high density > 0.959

Mechanical PropertiesBranched LowDensity

MediumDensity

HighDensity

Linear High Density

Density 0.91- 0.925 0.926- 0.94 0.941-0.95 0.959-0.965

Crystallinity 30% to 50% 50% to 70% 70% to 80% 80% to 91%

MolecularWeight

10K to 30K 30K to 50K 50K to 250K 250K to 1.5M

TensileStrength, psi

600 - 2,300 1,200 - 3,000 3,100 - 5,500 5,000 – 6,000

TensileModulus, psi

25K – 41K 38K – 75 K 150K – 158K

150K – 158 K

TensileElongation, %

100% - 650% 100%- 965% 10% - 1300% 10% - 1300%

Impact Strengthft-lb/in

No break 1.0 – nobreak

0.4 – 4.0 0.4 – 4.0

Hardness, Shore D44 – D50 D50 – D60 D60 – D70 D66 – D73

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Physical Properties of Polyethylene

Physical Properties of polyethyleneBranched LowDensity

Medium Density HighDensity

Linear High Density

Optical Transparent toopaque

Transparent toopaque

Transparent toopaque

Transparent to opaque

Tmelt 98 – 115 C 122 – 124 C 130 – 137 C 130 –137 C

Tg -100 C -100 C -100 C -100 CH20 Absorption Low < 0.01 Low < 0.01 Low < 0.01 Low < 0.01

OxidationResistance

Low, oxidesreadily

Low, oxidesreadily

Low, oxides readily Low, oxides readily

UV Resistance Low, Crazesreadily

Low, Crazesreadily

Low, Crazes readily Low, Crazes readily

SolventResistance

Resistantbelow 60C

Resistant below60C

Resistant below 60C Resistant below 60C

AlkalineResistance

Resistant Resistant Resistant Resistant

AcidResistance

OxidizingAcids

Oxidizing Acids Oxidizing Acids Oxidizing Acids

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Processing Properties of Polyethylene

Processing Properties

Branched LowDensity

Medium Density HighDensity

Linear High Density

Tmelt 98 – 115 C 122 – 124 C 130 – 137 C 130 –137 C

Recommended TempRange (I:Injection, E:Extrusion)

I: 300F – 450FE: 250F – 450F

I: 300F – 450FE: 250F – 450F

I: 350F – 500FE: 350F – 525F

I: 350F – 500FE: 350F – 525F

Molding Pressure 5 – 15 psi 5 – 15 psi 12 – 15 psi 12– 15 psi

Mold (linear) shrinkage(in/in)

0.015 – 0.050 0.015 – 0.050 0.015 – 0.040 0.015 – 0.040

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Special Low Versions of PolyethyleneProduced through catalyst selection and regulation of reactor conditions

• Very Low Density Polyethylene (VLDPE)– Densities between 0.890 and 0.915– Applications include disposable gloves, shrink packages,

vacuum cleaner hoses, tuning, bottles, shrink wrap, diaper film liners, and other health care products

• Linear Low Density Polyethylene (LLDPE)– Densities between 0.916 and 0.930– Contains little if any branching– Properties include good flex life, low warpage, and improved stress-

crack resistance– Applications include films for ice, trash, garment, and produce bags

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Special High Versions of PolyethyleneProduced through catalyst selection and regulation of reactor conditions

• High Molecular Weight- High Density Polyethylene (HMW-HDPE)– Densities are 0.941 or greater– MW from 200K to 500 K– Properties include improved toughness, chemical resistance,

impact strength, and high abrasion resistance. – High viscosities– Applications include trash liners, grocery bags, industrial pipe,

gas tanks, and shipping containers

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Special High Versions of PolyethyleneProduced through catalyst selection and regulation of reactor conditions

• Ultra High Molecular Weight Polyethylene (UHMWPE)– Densities are 0.96 or greater– MW from 3M to 6M– Properties include improved high wear resistance, chemical inertness,

and low coefficient of friction. – High viscosities result in material not flowing or melting.– Processed similar to PTFE (Teflon)– Ram extrusion and compression molding are used.– Applications include pump parts, seals, surgical implants, pen tips, and

butcher-block cutting surfaces.

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Copolymers of Polyethylene• Ethylene-ethyl acrylate (EEA)

– Properties range from rubbery to tough ethylene-like properties– Applications include hot melt adhesives, shrink wrap, produce bags, bag-

in-box products, and wire coating.• Ethylene-methyl acrylate (EMA)

– Produced by addition of methyl acrylate monomer (40% by weight)with ethylene gas

– Tough, thermally stable olefin with good elastomeric characteristics.– Applications include food packaging, disposable medical gloves, heat-

sealable layers, and coating for composite packaging

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Copolymers of Polyethylene• Ethylene-Vinyl Acetate (EVA)

– Repeating groups is ethylene with an acetate functional– Part of the pendent group are highly polar.– Vinyl acetate reduces crystallinity and increases chemical reactivity because

of high regions of polarity.– Result:flexible polymer that bonds well to other materials– Excellent adhesive (Elmers Glue)– Other applications include flexible packaging, shrink wrap, auto bumper

pads, flexible toys, and tubing

C C

H H

H H

C C

H OC = OC

H H

n m

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Copolymers of Polyethylene• Ethylene-Propylene (EPM)

– Ethylene and propylene are copolymerized in random manner and causes a delay in the crystallization.

– Thus, the copolymer is rubbery at room temp because the Tg is between HDPE (-110C) and PP (-20C).

– Ethylene and propylene can be copolymerized with small amounts of a monomer containing 2 C=C double bonds (dienes)

– Results in a ter polymer, EPDM, or thermoplastic rubber, TPO

C C

H H

H H

n

C C

CH3 H

H H

m

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Mechanical Properties of PE Blends

Mechanical Properties of PE Blends

Ethylene-vinylacetate

Ethylene-vinylalcohol

Ethylene-ethyl acrylate

Ethylene-methylacrylate

Density 0.922 – 0.943 1.14 – 1.19 0.93 0.942 – 0.945

TensileStrength, psi

2,200 – 4,000 8,520 – 11,600 1,600 – 2,100 1,650

TensileModulus, psi

7K – 29K 300 K – 385 K 4K – 7.5 K 12 K


300% - 750% 180%- 280% 700% - 750% 740%


No break 1.0 – 1.7 No break

Hardness, Shore D17 – D45 D27 – D38

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Processing Properties of PE Blends

Processing PropertiesEthylene-vinylacetate

Ethylene-vinylalcohol

Ethylene-ethylacrylate

Ethylene-methylacrylate

Tmelt 103 – 108 C 142 – 181 C 83 C

Recommended TempRange (C: Compression) (I:Injection, E:Extrusion)

C: 200-300FI: 300F – 430FE: 300F – 380F

I: 365F – 480FE: 365F – 480F

C: 200 – 300FI: 250F – 500F

E: 300F – 620F

Molding Pressure 1 – 20 psi 1 – 20 psi


0.007 – 0.035 0.015 – 0.035

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Polypropylene History • Prior to 1954 most attempts to produce plastics

from polyolefins had little commercial success• PP invented in 1955 by Italian Scientist F.J.

Natta by addition reaction of propylene gas with a sterospecific catalyst titanium trichloride.

• Isotactic polypropylene was sterospecific (molecules are arranged in a definite order in space)

• Polypropylene is similar in manufacturing method and in properties to PE

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Chemical Structure• Propylene

• Isotactic- CH3 on one side of polymer chain (isolated). Commercial PP is 90% to 95% Isotactic

C C

CH3 H

H H

C C

CH3 H

H H

C C

CH3 H

H H

C C

CH3 H

H H

C C

CH3 H

H H

C C

CH3 H

H H

n

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Polypropylene Stereostatic Arrangements

•Atactic- CH3 in a random order (A- without; Tactic- order) Rubbery and of limited commercial value.

•Syndiotactic- CH3 in a alternating order (Syndio- ; Tactic- order)

C C

CH3 H

H H

C C

H H

H CH3

C C

CH3 H

H H

C C

H H

H CH3

C C

CH3 H

H H

C C

CH3 H

H H

C C

H H

H CH3

C C

H H

H CH3

C C

CH3 H

H H

C C

H H

H CH3

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Addition Polymerization of PP• Polypropylene produced with low pressure process (Ziegler) • Polypropylene produced with linear chains• Polypropylene is similar in manufacturing method and in properties to PE• Differences between PP and PE are

– Density: PP = 0.90; PE = 0.941 to 0.965– Melt Temperature: PP = 176 C; PE = 110 C– Service Temperature: PP has higher service temperature– Hardness: PP is harder, more rigid, and higher brittle point– Stress Cracking: PP is more resistant to environmental stress cracking

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Advantages of Polypropylene• Advantages

– Low Cost– Excellent flexural strength– Good impact strength– Processable by all thermoplastic equipment– Low coefficient of friction– Excellent electrical insulation– Good fatigue resistance– Excellent moisture resistance– Service Temperature to 126 C– Very good chemical resistance

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Disadvantages of Polypropylene

• Disadvantages– High thermal expansion– UV degradation– Poor weathering resistance– Subject to attack by chlorinated solvents and aromatics– Difficulty to bond or paint– Oxidizes readily– flammable

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Molecular Weight Review• Molecular Weight estimates the average length of the polymer chain and is similar to the DP (degree of

polymerization)– MW = (MW of mer) x DP

• Example: MW= 100,000 for PS then the DP = 1000. (PS = 104 amu)• Example: MW= 50,000 for PE then the DP = 1800. (PE = 28 amu)

• Molecular Weight is measured by osmometry, light scattering and solution viscosity• Molecular Weight is characterized by Weight Average, Mw, and Number Average, Mn.• Polydispersity, PD

– Ratio of Mw / Mn

Weight

Frequency

Mw

Mn

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Mechanical Properties of Polypropylene Mechanical Properties of Polypropylene

Polypropylene LDPE(For Comparison)

HDPE(For Comparison)

Density 0.90 0.91- 0.925 0.959-0.965

Crystallinity 30% to 50% 30% to 50% 80% to 91%

Molecular Weight 200K to 600K 10K to 30K 250K to 1.5M

Molecular WeightDispersity MWD(Mw/Mn)

Range ofMWD forprocessing

Range of MWDfor processing

Range of MWDfor processing

Tensile Strength,psi

4,500 – 5,500 600 - 2,300 5,000 – 6,000

Tensile Modulus,psi

165K – 225K 25K – 41K 150K – 158 K


100% - 600% 100% - 650% 10% - 1300%


0.4 – 1.2 No break 0.4 – 4.0

Hardness, Shore R80 - 102 D44 – D50 D66 – D73

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Physical Properties of Polyethylene

Physical Properties of Polypropylene

Polypropylene LDPE HDPEOptical Transparent to

opaqueTransparent toopaque

Transparent to opaque

Tmelt 175 C 98 – 115 C 130 –137 C

Tg -20 C -100 C -100 CH20Absorption

0.01 – 0.03 Low < 0.01 Low < 0.01

OxidationResistance

Low, oxidesreadily

Low, oxidesreadily

Low, oxides readily

UV Resistance Low, Crazesreadily

Low, Crazesreadily

Low, Crazes readily

SolventResistance

Resistantbelow 80C

Resistant below60C

Resistant below 60C

AlkalineResistance

Resistant Resistant Resistant

AcidResistance

OxidizingAcids

Oxidizing Acids Oxidizing Acids

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Processing Properties of Polyethylene

Processing PropertiesPolypropylene LDPE HDPE

Tmelt 175 C 98 – 115 C 130 –137 C


I: 400F – 550FE: 400F – 500F

I: 300F – 450FE: 250F – 450F

I: 350F – 500FE: 350F – 525F

Molding Pressure 10 -20 psi 5 – 15 psi 12– 15 psi


0.010 – 0.025 0.015 – 0.050 0.015 – 0.040

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Copolymers of Polypropylene• Ethylene-propylene copolymers

– Small amount of PP can lower crystallinity of linear HDPE• Polyallomers (block copolymers)

– Blocks of PE and PP polymers allows crystallization to take place– Properties are similar to HDPE and PP

• Ethylene-propylene rubbers – Random co-polymerization of ethylene and propylene prevents crystallization of the chains

by suppressing regularity of molecules– Resulting polymers are amorphous having low Tg (between -110C and -20C depending on

% of PE and PP)– Polymers are rubbery at room temperature– Conventional vulcanization allows for use as commercial rubber, thermoplastic rubbers,

TPR

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Polyolefin_Polybutylene

• History

– PB invented in 1974 by Witco Chemical– Ethyl side groups in a linear backbone

• Description– Linear isotactic material– Upon cooling the crystallinity is 30%– Post-forming techniques can increase crystallinity to 55%– Formed by conventional thermoplastic techniques

• Applications (primarily pipe and film areas)– High performance films– Tank liners and pipes– Hot-melt adhesive – Coextruded as moisture barrier and heat-sealable packages

C C

CH2 H

H H

CH3

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Properties of Polybutylene

Mechanical Properties of PolybutylenePolybutylene Polypropylene LDPE

(For Comparison)HDPE(For Comparison)

Density 0.908 -.917 0.90 0.91- 0.925 0.959-0.965

Crystallinity 30% to 50% 30% to 50% 30% to 50% 80% to 91%


4,000 4,500 – 5,500 600 - 2,300 5,000 – 6,000

Tensile Modulus,psi

10K – 40K 165K – 225K 25K – 41K 150K – 158 K


300% - 400% 100% - 600% 100% - 650% 10% - 1300%


No break 0.4 – 1.2 No break 0.4 – 4.0

Hardness Shore D55 – D65 R80 - 102 D44 – D50 D66 – D73

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Polyolefin_Polymethylpentene (PMP)

• Description– Crystallizes to 40%-60% – Highly transparent with 90% transmission– Formed by injection molding and blow molding

• Properties– Low density of 0.83 g/cc; High transparency – Mechanical properties comparable to polyolefins with higher

temperature properties and higher creep properties.– Low permeability to gasses and better chemical resistance– Attacked by oxidizing agents and light hydrogen carbon solvents– Attacked by UV and is quite flammable

• Applications – Lighting elements (Diffusers, lenses reflectors), liquid level– Food packaging containers, trays, and bags.

C C

CH2 H

H H

H3C-CH-CH3

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Properties of Polymethylpentene

Mechanical Properties of Polymethylpentene

Polymethyl-pentene

Polypropylene LDPE(For Comparison)

HDPE(For Comparison)

Density 0.83 0.90 0.91- 0.925 0.959-0.965

Crystallinity 40% to60% 30% to 50% 30% to 50% 80% to 91%


4,000 – 5,000 4,500 – 5,500 600 - 2,300 5,000 – 6,000

Tensile Modulus,psi

160K – 200K 165K – 225K 25K – 41K 150K – 158 K


100% - 400% 100% - 600% 100% - 650% 10% - 1300%


0.4 – 1.0 0.4 – 1.2 No break 0.4 – 4.0

Hardness R80 – R100 R80 - 102 D44 – D50 D66 – D73

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PVC Background • Vinyl is a varied group- PVC, PVAc, PVOH, PVDC, PVB

– Polyvinyls were invented in 1835 by French chemist V. Regnault when he discovered a white residue could be synthesized from ethylene dichloride in an alcohol solution. (Sunlight was catalyst)

– PVC was patented in 1933 by BF Goodrich Company in a process that combined a plasticizer, tritolyl phosphate, with PVC compounds making it easily moldable and processed.

– PVC is the leading plastic in Europe and second to PE in the US.– PVC is made by suspension process (82%), by mass polymerization (10% ), or

by emulsion (8%)– All PVC is produced by addition polymerization from the vinyl chloride

monomer in a head-to-tail alignment.– PVC is amorphous with partially crystalline (syndiotactic) due to structural

irregularity increasing with the reaction temperature.– PVC (rigid) decomposes at 212 F leading to dangerous HCl gas

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PVC and Vinyl Products• Rigid-PVC

– Pipe for water delivery– Pipe for structural yard and garden structures

• Plasticizer-PVC or Vinyl– Latex gloves– Latex clothing– Paints and Sealers– Signs

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PVC and PS Chemical Structure• Vinyl Groups (homopolymers produced by addition polymerization)

– PVC - poly vinylidene - polyvinylalcohol (PVOH) chloride (PVDC)

– polyvinyl acetate (PVAc) - PolyStyrene (PS)

C C

H OCOCH3

H H

C C

H Cl

H H

n

C C

H Cl

H Cl

n

n

C C

H OH

H H

n

C C

H

H H

n

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Mechanical Properties of Polyvinyls Mechanical Properties

PVC (rigid) PVC (Flexible) PVB PVDCDensity, g/cc 1.30-1.58 1.16-1.35 1.05 1.65-1.72


6,000 - 7,500 1,500 -3,500 500 - 3,000 3,500 - 5,000

Tensile Modulus,psi

350K – 600K 160K –240K


40% - 80% 200%-450% 150% - 450% 160% -240%


0.4 - 22 Range Range 0.4 - 1

Hardness Shore D65-85 Shore A50-100 M60-65

CLTE10-6 mm/mm/C

50 -100 70-250 190

HDT 264 psi 140 F -170F 130F -150F

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Physical Properties of Polyvinyls

PVC (rigid) PVC (Flexible) PVB PVDC

Optical Transparent Transparent Transparent Transparent

Tmelt 75 – 105 C 75 – 105 C 49 172C

Tg 75 -105C 75-105C 49 -15C

H20Absorption

0.04-0.4% (24h) 0.15-0.75% (24h) 0.09-0.16% (24h) 0.1% (24h)

OxidationResistance

good good good good

UV Resistance Poor Poor Poor good

SolventResistance

Soluble inAcetone, and

Cyclohexanol.Partially in

Toluene

Soluble inAcetone, and

Cyclohexanol.Partially in

Toluene

Dissolved in ketonesand esters

good

AlkalineResistance

Excellent Excellent Excellent good

AcidResistance

good good good good

Cost $/lb $0.27 $0.27 $ $1.62

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Processing Properties of Polyvinyls

PVC (rigid) PVC (Flexible) PVB PVDCTmelt 75 – 105 C 75 – 105 C 49 172C

Recommended TempRange (I:Injection, E:Extrusion,C: Compression)

I: 300F – 415FC: 285F-400F

I: 320F – 385FC: 285F - 350F

I: 250F – 340FC: 280F-320F

I: 300F – 400FC: 260F-350FE: 300F-400F

Molding Pressure 10-40 kpsi 8-25 kpsi 0.5-3kpsi 5 - 30 kpsi


0.002 – 0.006 0.010 – 0.050 0.005 - 0.025

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PS Background • PS is one of the oldest known vinyl compounds

– PS was produced in 1851 by French chemist M. Berthelot by passing benzene and ethylene through a red-hot-tube (basis for today)

– Amorphous polymer made from addition polymerization of styrene– Homopolymer (crystal): (2.7 M metric tons in 1994)

• Clear and colorless with excellent optical properties and high stiffness.• It is brittle until biaxially oriented when it becomes flexible and durable.

– Graft copolymer or blend with elastomers- Impact polystyrene (IPS): • Tough, white or clear in color, and easily extruded or molded.• Properties are dependent upon the elastomer %, but are grouped into

– medium impact (Izod<1.5 ft-lb), high impact (Izod between 1.5 to 2.4 ft-lb) and super-high impact (Izod between 2.6 and 5 ft-lb)

– Copolymers include SAN (poly styrene-acrylonitrile), SMA (maleic anhydride), SBS (butadiene), styrene and acrylic copolymers.

– Expandable PS (EPS) is very popular for cups and insulation foam. • EPS is made with blowing agents, such as pentane and isopentane. • The properties are dependent upon cell size and cell size distribution

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Mechanical Properties of PS, ABS, SAN

Mechanical PropertiesPS ABS SAN

Density, g/cc 1.04 1.16-1.21 1.07


5,000 - 7,200 3,300 - 8,000 10,000 -12,000

Tensile Modulus,psi

330K-475K 320K-400K 475K-560K


1.2% - 2.5% 1.5%-25% 2%-3%


0.35-0.45 1.4-12 0.4-0.6

Hardness M60-75 R100-120 R83, M80

CLTE10-6 mm/mm/C

50 -83 65- 95 65-68

HDT 264 psi 169F - 202F 190F - 225F 214F - 220F

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Physical Properties of PS, ABS, SAN

PS ABS SAN

Optical Transparent Transparent Transparent

Tmelt 100 C 125C 120C

Tg 75 -105C 110 -125C 120C

H20Absorption

0.01-0.03% (24h) 0.2-0.6% (24h) 0.15-0.25% (24h)

OxidationResistance

good good good

UV Resistance fair fair fair

SolventResistance

Soluble inAcetone, Benzene,

Toluene andMethylenedichloride

Soluble inToluene and

Ethylenedichloride,Partially inBenzene

Dissolved in ketonesand esters

AlkalineResistance

Excellent Excellent Poor: attacked byoxidizing agents

AcidResistance

Poor: attacked byoxidizing agents

Poor: attacked byoxidizing agents

good

Cost $/lb $0.41 $0.90 $0.87

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Processing Properties of PS, ABS, SAN

PS ABS SANTmelt 100 C 125C 120C


I: 350F – 500FE: 350F- 500FC: 300F - 400F

I: 380F – 500FC: 350F - 500F

I: 360F – 550FE: 360F -450FC:300F - 400F

Molding Pressure 5 - 20 kpsi 8-25 kpsi 5-20 kpsi


0.004 – 0.007 0.004 – 0.008 0.003 – 0.005

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Section Review • Major Topics

– Vinyl is a varied group- PVC, PVAc, PVOH, PVDC, PVB.– PVC is the leading plastic in Europe and second to PE in the US.– PVC is produced by addition polymerization from the vinyl chloride monomer

in a head-to-tail alignment.– PVC is partially crystalline (syndiotactic) with structural irregularity increasing

with the reaction temperature.– PVC (rigid) decomposes at 212 F leading to dangerous HCl gas X1– Vinyls have (CH2CX2) repeating link– PS is Amorphous and made from addition polymerization– PC is amorphous and made from condensation polymerization – Effects of reinforcements on PP and PS

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Homework Questions

6. Four typical Physical Properties of PVC are Optical = _______, Resistance to moisture= ______ , UV resistance= _____, solvent resistance=_______

7. The Advantages of PP are ________, ________, _______, and __________.

8. The Disadvantages of PP are ________, ________, _______, and __________.

9. Glass fiber affects PP by (strength) ________, (modulus)________, (impact)_______, (density) __________, and (cost) ____________.

10. Two Blends PVC are ___________, and __________.

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Section Review • Major Topics

– Isotactic, atactic, sydiotactic polypropylene definitions– Differences between PP and PE– Molecular Weight definition and forms (Weight Average,

Mw, and Number Average, MA )– Polydispersity definition and meaning– Relation between Molecular weight and Degree of

Polymerization (DP)– Mechanical, physical, and processing properties of PP,

Polybutylene, and polymethylpentene– PP is produced with linear chains

46

Section Review

• Key Terms and Concepts– Polyolefin– Molecular weight– Number average molecular weight, weight average MW– Polydispersity– Polymer shrinkage– Polymer blends– Tensile Modulus– Izod Impact Strength

47

Homework Questions1. Define Polyvinyls, PS, PP, HDPE, chemical structure.

2. Compare the density PVC, PVB, PS, and PVDC which is higher/lower than PP.

3. Compare the density of HDPE, LDPE, UHMWPE, LLDPE to PP?

4. What is the tensile strength of PP with 0%, 30% glass fibers? What is the tensile modulus?

5. Plot tensile strength and tensile modulus of PVC, PS, PP, LDPE and HPDE to look like:

Tensile Strength,Kpsi

Tensile Modulus, Kpsi200 500

10

50

xLDPE

xHDPE

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Homework Questions1. Define Polypropylene chemical structure2. Does commercial PP have Isotactic, atactic, sydiotactic form.3. If MW of PP is 200,000, what is the approx. DP?4. Polydispersity represents the distribution of _______and _____5. Density of PP is _____ which is higher/lower than HDPE.6. PP mechanical properties are higher/lower than LDPE and HDPE7. Plot tensile strength and tensile modulus of PP, LDPE and HPDE to

look like the following

Tensile Modulus,Kpsi

Tensile Strength, Kpsi2 5

10

50

xLDPE

xHDPE

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Homework Questions8. Four typical Physical Properties of PP are Optical = _______, Resistance

to moisture= ______ , UV resisance= _____, solvent resistance=_______ 9. The Advantages of PP are ________, ________, _______, and

__________.10. The Disadvantages of PP are ________, ________, _______, and

__________.11. Glass fiber affects PP by (strength) ________, (modulus)________,

(impact)_______, (density) __________, and (cost) ____________.12. Five polyolefins are ________, ________, _______, ______, and

__________.

Documents

Commodity Thermoplastics_ LDPE, HDPE, PP, PVC, PS