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

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Presentation on theme: "1 Commodity Thermoplastics_ LDPE, HDPE, PP, PVC, PS Professor Joe Greene CSU, CHICO."— Presentation transcript:

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

2 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 3 Principal Olefin Monomers Ethylene Propylene Butene-1 4-Methylpentene CC HH HH CC C2H5C2H5 H HH CC CH 3 H HH CC C5H6C5H6 H HH

4 4 Several Olefin Polymers Poly Ethylene Poly Propylene PolyisoButene PolyMethylpentene CC C2H5C2H5 H HH n CC C5H6C5H6 H HH CH 3 n CC HH HH n CC H HH n

5 5 Polymers Derived from Ethylene Monomer

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

7 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 8 Physical Properties of Polyethylene

9 9 Processing Properties of Polyethylene

10 10 Special Low Versions of Polyethylene Produced through catalyst selection and regulation of reactor conditions Very Low Density Polyethylene (VLDPE) –Densities between and –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 –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 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 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 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 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 CC H H HH CC H O C = O C HH n m

15 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 CC H H HH n CC CH 3 H HH m

16 16 Mechanical Properties of PE Blends

17 17 Processing Properties of PE Blends

18 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 19 Chemical Structure Propylene Isotactic- CH 3 on one side of polymer chain (isolated). Commercial PP is 90% to 95% Isotactic CC CH 3 H HH CC H HH CC H HH CC H HH CC H HH CC H HH n

20 20 Polypropylene Stereostatic Arrangements Atactic- CH 3 in a random order (A- without; Tactic- order) Rubbery and of limited commercial value. Syndiotactic- CH 3 in a alternating order (Syndio- ; Tactic- order) CC CH 3 H HH CC H H H CC H HH CC H H H CC H HH CC H HH CC H H H CC H H H CC H HH CC H H H

21 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 –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 22 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

23 23 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

24 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, M w, and Number Average, M n. Polydispersity, PD –Ratio of M w / M n Weight Frequency MwMw MnMn

25 25 Mechanical Properties of Polypropylene

26 26 Physical Properties of Polyethylene

27 27 Processing Properties of Polyethylene

28 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 29 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 CC CH 2 H HH CH 3

30 30 Properties of Polybutylene

31 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. CC CH 2 H HH H 3 C-CH-CH 3

32 32 Properties of Polymethylpentene

33 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 34 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

35 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) CC HOCOCH 3 HH CC HCl HH n CC H H n n CC HOH HH n CC H HH n

36 36 Mechanical Properties of Polyvinyls

37 37 Physical Properties of Polyvinyls

38 38 Processing Properties of Polyvinyls

39 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 40 Mechanical Properties of PS, ABS, SAN

41 41 Physical Properties of PS, ABS, SAN

42 42 Processing Properties of PS, ABS, SAN

43 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 (CH 2 CX2) 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 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 45 Section Review Major Topics –Isotactic, atactic, sydiotactic polypropylene definitions –Differences between PP and PE –Molecular Weight definition and forms (Weight Average, M w, and Number Average, M A ) –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 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 47 Homework Questions 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: Tensile Strength, Kpsi Tensile Modulus, Kpsi xLDPE xHDPE

48 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 Tensile Modulus, Kpsi Tensile Strength, Kpsi xLDPE xHDPE

49 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 __________.


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