Plastic Product Material and Process Selection Handbook Part 4 pps

2 9 Plastic property 53 Melt index is close to 3.5, tensile strength about 1,500 psi (6.9 MPa), melting point of 99 to 100C, and needle penetration test at 25C is 1 to 10. Just over 10wt% of LDPE produced in the USA find use in typical wax applications, such as paper coatings and floor polishes. A major use is coated paperboard for milk cartons. Chlorinated Polyethylene Elastomers The moderate random chlorination of polyethylene suppresses crystallinity and yields chlorinated polyethylene elastomer (CPE), a rubber-like material that can be crosslinked with organic peroxides. The chlorine (CI) content is in the range of 36 to 42%, compared to 56.8% for PVC. Such elastomer has good heat and oil resistance. It is also used as a plasticizer for PVC. They provide a very wide range of properties from soft/elastomeric too hard. They have inherent oxygen and ozone resistance, resist plasticizers, volatility, weathering, and compared to PEs have improved resistance to chemical extraction. Products do not fog at high temperatures as do PVCs and can be made flame retardant. I"olym thylp t Major advantages of PMP over other polyolefins are its transparency in thick sections, its short-time heat resistance up to 200C (400F), and its lower specific gravity. It differs from other polyolefins since it is transparent because its crystalline and amorphous phases have the same index of refraction. Almost clear optically PMP has a light transmission value of 90% that is just slightly less than that of the acrylics. It retains most of its physical properties under brief exposure to heat at 200C (400F), but it is not stable at temperatures for an extended time over 150C (300F) without an antioxidant. In a clear form it is not recommended where it will have to undergo long-term exposure to UV environments. Chemical resistance and electrical properties of PMP arc similar to those of the other polyolefins, except that it retains these properties at higher temperatures than do either PE or PP. In this respect PMP tends to compare well with PTFE up to 150C (300F). Molded parts made of this plastic are hard and shiny, yet their impact strength is high at temperatures down to-29C (-20F). Their specific gravity of 0.83 is the lowest of many commercial solid plastics. Polyolefin Elastomer POE and polyolcfin plastomcrs (POP) arc ethylene alpha olcfin copolymcrs produced using constrained geometry and metallocenc catalyst. They differ from traditional polyolefins in that thcy have narrow molecular weight distribution and a regular placement of the octcnc co-monomer on the ethylene backbone. This highly uniform distribution allows for some unique plastic characteristics. 90 Plastic Product Material and Process Selection Handbook biodegradable It is reported to be the first plant that has been genetically engineered to make something other than a protein. Britain's ICI previously made PHB using a soil bacteria acaligenes eutrophus that is being used in blow and injection molding. Researcher's at Michigan used three genes identified and cloned from the bacteria ICI used in 1987. Polyimidazole A variety of polymidazoles can be prepared by aromatic nucleolphilic displacement, from the reactions of bisphenol imidazoles with activated difluoro compounds. These plastics have good mechanical properties that make them suitable for use as films, moldings, and adhesives. Polyimide The first so-called high-heat-resistant TPs were the PIs a family of some of the most heat- and fire-resistant plastics known. They are available in both TPs and TSs. Moldings and laminates are generally based on TSs, though some are made from TPs. PIs are available as laminates and in various shapes, as molded parts, stock shapes, and plastics in powders and solutions. Porous PI parts are also available. Uses include critical engineering parts in aerospace, automotive and electronics components subject to high heat, and in corrosive environments. Parts include wire enamel, insulating varnish, and coated glass fabrics. The insulating varnish possesses good electrical properties in the-190 to 340C (-310 to 644F) temperature range. Generally, the compounds that are the most difficult to fabricate are also the ones that have the highest heat resistance. They have a density of 1.41 to 1.43, tensile strength of 12,000 psi at 73F, and an elongation of 6.8% at that same temperature. They have a low coefficient of expansion. PIs retain a significant portion of their room temperature mechanical properties from-240 to 315C (-400 to + 600F) in air. The service temperature for the intermittent exposure of PIs can range from cryogenic to as high as 480C (900F). Their deformation under a 28 MPa (4.000 psi) load is less than 0.05% at room temperature for twenty-four hours. Glass-fiber reinforced PIs retain 70% of their flexural strength and modulus at 250C (480F). Creep is almost nonexistent, even at high temperatures. These materials have good wear resistance and a low coefficient of friction, both of which are factors that can be further improved by including additives like PTFE. Self-lubricating parts containing graphite powders have flexural strengths above 69 MPa (10,000 psi.) Their 2 9 Plastic property 55 PP is widely known for its application in the integral so called living hinges that are used in all types of applications; PP's excellent fatigue resistance is utilized in molding these integral living hinges. 59 They have superior resistance to flexural fatigue stress cracldng, with excellent electrical and chemical properties. This versatile polyolefin overcomes poor low temperature performance and other shortcomings through copolymer, filler, and fiber additions. It is widely used in packaging (film and rigid), and in automobile interiors, under-the-hood and underbody applications, dishwashers, pumps, agitators, tubs, filters for laundry appliances and sterilizable medical components, etc. 96 Electrical properties are affected to varying degrees by their service temperatures. Its dielectric constant is essentially unchanged, but its dielectric strength increases and its volume resistivity decreases as temperature increases. They are unstable in the presence of oxidation conditions and UV radiation. Although all its grades arc stabilized to some extent, specific stabilization systems are often used to suit a formulation to a particular environment, such as where it must undergo outdoor weathering. PPs resist chemical attack and staining and are unaffected by aqueous solutions of inorganic salts or mineral acids and bases, even at high temperatures. Most organic chemicals do not attack them, and there is no solvent for this plastic at room temperature. Halogens, fuming nitric acid, and other active oxidizing agents attack the plastics. Also attacked by aromatic and chlorinated hydrocarbons at high temperatures. PPs have limited heat resistance, but heat-stabilized grades are available for applications requiring prolonged use at elevated temperatures. The useful life for products molded from such grades may be at least as long as five years at 120C (250F), 10 years at 130C (230F), and 20 years at 99C (210F). Specially stabilized grades are UL rated at 120C (248F) for continuous service. Basically, PP is classified as a slow burning material, but it can also be supplied in flame-retardant grades. Polybutylene Part of the polyolcfin family are PBs. They are similar to PPs and HDPEs but exhibit a more crystalline structure. This crystallinity produces unusual high strength and extreme resistance to deformation over a temperature range of-10 to 190F. Its structure results in a rubberlikc, elastomeric material with low molded-in stress. Tensile stress that does not plateau after reaching its yield point makes possible films that look like PE but act more like polyester (TP) films. Compared to other polyolefins, they have superior resistance to creep 92 Plastic Product Material and Process Selection Handbook Polyketone PK are crystalline engineering TPs that provide high performing thermal, mechanical, chemical, and electrical properties. They are used in a variety of products for the electrical, automotive, aerospace, chemical, and oil industries. They compete for applications with ceramics, glass, metals, thermoset plastics, and heat-tolerant and chemical resistant engineering thermoplastics such as polysulfone, polyimide, polycarbonate, fluoropolymer, and some nylons. The family of PI~, also called polyaryletherketones (PAEKs), consists of polyether- etherketone (PEEK), polyetheretherketoneketone (PEEKK), polyether- ketone (PEK), and polyetherketoneetherketoneketone (PEKEKK). They share similar molecular structures based upon repeating ether and ketone groups in various ratios. Polyetheretherketone With its flexibility, PEEK behaves like a true TP and has the ability to crystallize (25 to 50%). Its high glass transition temperature (Tg) and the high melting point (Tin) , combined with high temperature chemical stability, rate this plastic in the most temperature resistant TPs. As with other crystallizing TPs, crystallinity can develop only at temperatures between Tm and Tg, a fact that must be taken into account for processing (extrusion, injection, etc.). PEEK retains good mechanical properties at high temperatures such as 200C (392F) for periods of time. They have a very low flammability and very low smoke and toxic gas emission. It is practically insoluble in any solvents and particularly resistant to hydrolysis by steam or high temperature pressurized water, absorbs little moisture, and has excellent resistance to nuclear radiation. As other crystallizing materials, it is resistant to environmental stress cracking. Polyetheretherketoneketone PEEKK provides high performance plastics that meet the growing requirement for thermal stability and mechanical strength in the electronics, automotive, and mechanical engineering industries. Their chemical bonds rank among the most stable ones in organic chemistry. The molecules are closely packed over wide areas, forming crystalline regions. This crystallinity with the chemical nature of PEEK3( provides its exceptional performance. Its most important property has been its resistance to dimensional changes (softening) when exposed to high temperatures and also its resistant oxidation as it ages. Polylactide PLA is a biodegradable plastic. The first worldwide production facility for PLA opened by Cargill Dow LLC joint venture occurred at the end 2 9 Plastic property 57 and petroleum products. However, they should be kept away from chlorinated solvents, such as many household-cleaning fluids. Vinyls can withstand continuous exposure to heat up to 130F (54C) and perform satisfactorily at food freezing temperatures. 98q~ Most vinyls arc naturally clear, with an unlimited color range for most forms of the materials. They generally have in common excellent strength, abrasion resistance, and self-extinguishable. In their elastomeric form vinyls usually exhibit properties superior to those of natural rubber in their flcxural life, resistance to acids, alcohols, sunlight, wear, and aging. They are slow burning and some types are self-extinguishing but they should be kept away from direct heat. The vinyls may be given a wide range of colors and may be printed or embossed. They generally have excellent electrical properties but with relatively poor weathering qualities are recommended for indoor use only unless stabilized wit suitable additives. Vinyls literally can be processed by more techniques than any other plastic. Reason is that it contains a relatively polar polymer that allows a large range of formations. Polyvinyl Chloride The high volume PVCs worldwide market provides a wide range of low cost flexible to rigid plastic with moderate heat resistance and good chemical, weather and flame resistance. The manufacture of a wide range of products is possible because of PVC's miscibility with an amount and variety of plasticizers. PVC has good clarity and chemical resistance (Figures 2.2 and 2.3). PVC can be chlorinated (CPVC) and be alloyed with other polymers like ABS, acrylics, polyurethanes, and nitrile rubbers to improve its impact resistance, heat deflection, and processability. Although these vinyls differ in having literally thousands of varying compositions and properties, there are certain general characteristics that are common to nearly all these plastics. Most materials based on vinyls are inherently TP and heat sealable. The exceptions are the products that have been purposely compounded with TSs or crosslinldng agents arc used. Rigid PVC, so-called poor man's engineering plastic, has a wide range of properties for use in different products. It has high resistance to ignition, good corrosion, and stain resistance, and weatherability. However, aromatic solvents, ketones, aldehydes, naphthalenes, and some chloride, acetate, and acrylate esters attack it. In general, the normal impact grades of PVCs have better chemical resistance than the high-impact grades. Most PVCs arc not recommended for continuous use above 60C (140F). Chlorination to form CPVC increases its heat 94 Plastic Product Material and Process Selection Handbook reinforced compounds. Because of their hydrolytic stability, both at room and elevated temperatures, blended parts in PPE can be repeatedly steam sterilized with no significant change in their properties. When exposed to aqueous environments their dimensional changes are low and predictable. PPEs resistance to acid, bases and detergents are excellent. However. it is attacked by many halogenated or aromatic hydrocarbons. Foamable grades have service temperature ratings of up to 96C (205F) in 1/4 in. sections. PPE products are used in different applications. Their unique compatibility with PS, particularly HIPS, results in a wide range of high temperature, tough, dimensionally stable products. They can be processed by conventional equipment that produces either solid or foam products. Polyphenylene Oxide PPOs have high glass transition temperature (Tg). Both transparent and opaque grades are available. They have good hydrolytic resistance, are soluble in chlorinated and aromatic hydrocarbons, and have good mechanical and electrical properties over a wide temperature range [-170 to 190C (-274 to 374F)]. They are not so thermally stable as polyimides or polybenzimidazoles. The material has a brittle-point of -170C. Representative properties of the PPO include heat deflection temperature, 192 to 194C (375 to 399F) at 264 psi; tensile strength at yield, 75 MPa (11,000 psi); tensile modulus, 0.03 MPa (3.8 x 105 psi); tensile elongation at break, 5 to 6%; and flexural strength at yield, 100 MPa (14,500 psi). The PPOs can be injection molded (343C/8,000 to 12,000 psi) or extruded (288C) on standard equipment, and can be machined like brass. Melting point (Wm) is 260C (500F). Electrical properties are generally good and unaffected by moisture. Dielectric properties, in particular, are good and stable. They are classified as self-extinguishing and non-dripping. Hydrolytic stability is exceptionally high. it is also highly resistant to water, including hot water and steam. It can be repeatedly sterilized in steam autoclaves. Cost and certain processing difficulties associated with a high melt viscosity originally led to the use of blends (polyalloys) with PS or HIPS resulting in a single Tg about 150C (302F) to blends from 100 to 135C (212 to 57F). These lower Tg blends are often referred to as modified PPO (MPPO). The mechanical properties of MPPO are generally good with high stiffness and low creep over a wide temperature range. Good toughness extends to low temperatures. Excellent dimensional stability is associated with the noncrystalline [...]... ( 24 hrs.) Dielectric strength V per rail Dielectric cottsOnt (60-10* CPS) Dissipation (power factor 60 106 CPS) Arc resistance, sec Bumirtg rate Polyesters Epoxies Phenolics Melamines 1.10 I 4 Good None 0-high 600 (315) 0.25-0.8 >600 (315) 298 ( 148 ) >900 (48 2) 0.3-0.5 O 1-O.5 270 680 (132-360) O 11-0.60 200 -42 0 40 0-500 360 40 0 300 40 0 200-500 250-725 2.8-5.2 3.3-5,0 4. 0-7.5 4. 3-7.6 3.2-5,2 3.2-131.5 0.003-.028 0.002-... resistance, and general durability Polychloroprene See Neoprene 108 Plastic Product Material and Process Selection Handbook Polyd icycl o penta die ne PDCPD is a highly crosslinked polyolefin It is processed by reaction injection molding at low temperatures and pressures (Chapter 12) Its low viscosity and potential to extend gel times to a matter of minutes allow the production of very large parts Parts... for various degrees of impact resistance Clarity and gloss are 100 Plastic Product Material and Process Selection Handbook level at least equal to such workhorse crystalline plastics as nylon and acetal Isoplast have very low viscosity melts and can be molded with low injection pressures 3.5 to 14 MPa (500 to 2000 psi) even in large, difficult to fill parts or with high loadings of glass fiber During... ¢'D 1 1 8 Plastic Product Material and Process Selection Handbook TPOs allow easy recycling of production waste and final products made of TPOs Studies have shown that products can be manufactured from recycled TPOs without significant loss of performance This can be seen as a big advantage compared with traditional rubber, which is relatively difficult to recycle and usually leads to inferior products... relatively poor mechanical properties compared to other clastomers and plastics [as an example 1 14 Plastic Product Material and Process Selection Handbook tensile strength of 600 to 1,350 psi (4 to 9 MPa)] However these properties are retained over a very wide temperature range Typically, they have a useful life of about two years at 150C (300F) and retain their flexibility to a b o u t - 5 0 C (-60F) or... friction and of thermal expansion (0.000013 i n / i n / F ) PBIs have no known melting point Its has a glass transition temperature (Tg) of 42 7C (800F) They have ultrahigh heat distortion temperatures of 43 5C (815F), retards flame, and will not burn in air The material can withstand steady temperatures up to 42 7C (800F) and short bursts up to 760C (1 ,40 0F) The material resist steam at 343 C (650F) and 15... 1 12 Plastic Product Material and Process Selection Handbook floor coatings, marine finishes, etc A major use for soft-foam is automotive bumpers; another is upholstery Basically property improvements are made with added fibers and fillers in reaction molded products to improve cut strength resistance, stiffer moduli, reduce waviness caused by heat and weathering, etc See Polyurethane, Thermoplastic... adhcs~oa High cost Heat resistance -0 3 "1o O ¢.o 1 04 Plastic Product Material and Process Selection Handbook Diallyl Phthalate DAP and diallyl isophthalate (DAIP) are the principal thermosets in the allyl family with DAP predominantly used DAPs' major use is in electrical connectors since they perform well in electrical circuits Used also in RP laminates and molding compounds In some applications DAPs... electrical industry They have low creep, excellent dimensional stability, good water and chemical resistance, heat resistant, good weatherability, and have properties that are somewhat inferior to those of the more expensive TSs Molded black or brown opaque handles for cookware 106 Plastic Product Material and Process Selection Handbook Table 2~ Elastomer names ASTM designation : - - trade name IR IIR ABR . ( 140 F). Chlorination to form CPVC increases its heat 94 Plastic Product Material and Process Selection Handbook reinforced compounds. Because of their hydrolytic stability, both at room and. heat and for various degrees of impact resistance. Clarity and gloss are 100 Plastic Product Material and Process Selection Handbook level at least equal to such workhorse crystalline plastics. 13-36.5 15-21,5 IZ-15 40 -45 9-15 4. 7 -40 .0 10 -x PSI Flexural strength !0 ~ 8.5-18.5 13-21 11-17 11- 14 9- 14 7.1 -49 .5 PSI ln~act strength O~-od) 0.2 4 0.2-1.0 0,25-0 ,40 0. 24- 0 .40 0.25-6.0 0.25-0.8