1. Commodity Thermoplastics_ LDPE, HDPE, PP, PVC, PS
Professor Joe Greene
CSU, CHICO

2. 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

3. Principal Olefin Monomers
Ethylene Propylene
Butene Methylpentene C
CH3 H C H C
C5H6 H
CH3 C
C2H5 H

4. Several Olefin Polymers
Poly Ethylene Poly Propylene
PolyisoButene PolyMethylpentene C H n C
CH3 H n C
C5H6 H
CH3 n C
C2H5 H n

5. Polymers Derived from Ethylene Monomer
X Position
Material Name
Abbreviation H
Polyethylene PE Cl
Polyvinyl chloride
PVC
Methyl group
Polypropylene PP
Benzene ring
Polystyrene PS CN
Polyacrylonitrile
PAN
OOCCH 3
Polyvinyl acetate
PvaC OH
Polyvinyl alcohol
PVA
COOCH
Polymethyl acrylate
PMA F
Polyvinyl fluoride
PVF
Note :
Methyl Group is: |
H – C – H
Benzene ring is:

6. Addition Polymerization of PE
Polyethylene produced with low (Ziegler) or high pressure (ICI)
Polyethylene produced with linear or branched chains C H n OR C H n C H n

7. Mechanical Properties of Polyethylene
Type 1: (Branched) Low Density of g/cc
Type 2: Medium Density of g/cc
Type 3: High Density of g/cc
Type 4: (Linear) High Density to ultra high density > 0.959

8. Physical Properties of Polyethylene

9. Processing Properties of Polyethylene

10. Special Low Versions of Polyethylene Produced through catalyst selection and regulation of reactor conditions
Very Low Density Polyethylene (VLDPE)
Densities between 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 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

11. Special High Versions of Polyethylene Produced through catalyst selection and regulation of reactor conditions
High Molecular Weight- High Density Polyethylene (HMW-HDPE)
Densities are 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

12. Special High Versions of Polyethylene Produced 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.

13. 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

14. 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 H O
C = O C H n m

15. 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 H n
CH3 m

16. Mechanical Properties of PE Blends

17. Processing Properties of PE Blends

18. 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

19. Chemical Structure Propylene
Isotactic- CH3 on one side of polymer chain (isolated). Commercial PP is 90% to 95% Isotactic C
CH3 H n C
CH3 H

20. 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
CH3 H C
CH3 H

21. 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 = 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

22. Advantages of Polypropylene
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

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

24. 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 = (PS = 104 amu)
Example: MW= 50,000 for PE then the DP = (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

25. Mechanical Properties of Polypropylene

26. Physical Properties of Polyethylene

27. Processing Properties of Polyethylene

28. 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

29. Polyolefin_PolybutyleneC
CH2 H
CH3
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

30. Properties of Polybutylene

31. 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
CH2 H
H3C-CH-CH3

32. Properties of Polymethylpentene

33. 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

34. PVC and Vinyl Products Rigid-PVC Plasticizer-PVC or Vinyl
Pipe for water delivery
Pipe for structural yard and garden structures
Plasticizer-PVC or Vinyl
Latex gloves
Latex clothing
Paints and Sealers
Signs

35. 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 H Cl n C H OH n C H Cl n C H
OCOCH3 C H n n

36. Mechanical Properties of Polyvinyls

37. Physical Properties of Polyvinyls

38. Processing Properties of Polyvinyls

39. 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

40. Mechanical Properties of PS, ABS, SAN

41. Physical Properties of PS, ABS, SAN

42. Processing Properties of PS, ABS, SAN

43. 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

44. 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 __________.

45. 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 Questions 50 xHDPE Tensile Strength, Kpsi xLDPE 10 200 500
1. 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: 50
xHDPE
Tensile
Strength,
Kpsi
xLDPE 10
200
500
Tensile Modulus, Kpsi

48. Homework Questions 1. Define Polypropylene chemical structure
2. 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 HDPE
7. Plot tensile strength and tensile modulus of PP, LDPE and HPDE to look like the following 50
xHDPE
Tensile
Modulus,
Kpsi
xLDPE 10 2 5
Tensile Strength, Kpsi

49. Homework Questions
8. 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 __________.