Elastomers olefin

TEO thermoplastic elastomer olefinic TOC total organic carbon... 

Thermoplastic elastomer (or rubber) Thermoplastic elastomer - amide based Thermoplastic elastomer - olefin based Thermoplastic elastomer - urethane based Thermoplastic ether ester (COPE or PEEL) Thermoplastic ethylene propylene rubber - aTPE TP-EPDM... 

POM polyoxymethylene, polyformaldehyde, acetals TEE-O, TEO thermoplastic elastomer - olefinic... 

Aliphatic C-5—C-6. Aliphatic feedstreams are typically composed of C-5 and C-6 paraffins, olefins, and diolefins, the main reactive components being piperylenes cis-[1574-41 -0] and /n j -l,3-pentadiene [2004-70-8f). Other main compounds iaclude substituted C-5 and C-6 olefins such as cyclopentene [142-29-OJ, 2-methyl-2-butene [513-35-9] and 2-methyl-2-pentene [625-27-4J. Isoprene and cyclopentadiene maybe present ia small to moderate quaatities (2—10%). Most steam cracking operatioas are desigaed to remove and purify isoprene from the C-5—C-6 fraction for applications ia mbbers and thermoplastic elastomers. Cyclopentadiene is typically dimerized to dicyclopentadiene (DCPD) and removed from C-5 olefin—diolefin feedstreams duriag fractionation (19). 

Although p oly (a-olefin) s (PAO) and esters are the prominent synthetic base stocks for automotive appfications, combinations of the two are becoming the choice in offering a balance of properties such as additive solubility, sludge control, and elastomer compatibility (34). 

Densities and crystallinities of ethylene—a-olefin copolymers mosdy depend on their composition. The classification ia Table 1 is commonly used (ASTM D1248-48). VLDPE resias are usually further subdivided iato PE plastomers of low crystallinity, 10—20%, with densities ia the range of 0.915—0.900 g/cm, and completely amorphous PE elastomers with densities as low as 0.860 g/cm. ... 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

The more important grades of thermoplastic natural mbber, which fall into the olefinic class of thermoplastic elastomers, are prepared with the natural mbber phase partially cross-linked during blending, a process known as dynamic vulcanization. The hardness of the soft blends is controlled by the natural mbber content, and typical properties of those of 50—90 hardness (Shore A) are shown in Table 7. 

Polymerization. Polymerization reactions, which are addition reactions, are used to produce the principal products formed direcdy from butlylenes butyl elastomers polybutylenes and polyisobutylene (see Elastomers, synthetic Olefin polymers). 

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

Because of the unusual reactivity of the DCPD molecule, there are a number of wide and varying end use areas. The primary uses in the U.S. are DCPD-based unsaturated polyester resins (36%) hydrocarbon type resins, based on DCPD alone or with other reactive olefins (39%) EPDM elastomers via a third monomer ethylidenenorhornene or DCPD (16%) and miscellaneous uses (9%), including polychlorinated pesticides, polyhalogenated flame retardants, and polydicyclopentadiene for reaction injection mol ding (39). 

Prior to butyl mbber, the known natural and synthetic elastomers had reactive sites at every monomer unit. Unlike natural mbber, polychloroprene, and polybutadiene, butyl mbber had widely spaced olefin sites with aHyUc hydrogens. This led to the principle of limited functionahty synthetic elastomers that was later appHed to other synthetic elastomers, eg, chlorosulfonated polyethylene, siUcone mbber, and ethylene—propylene terpolymers. 

Ethylene-cyclo-olefin copolymers have been known since 1954 (DuPont USP2 721 189) but these materials only became of importance in the late 1990s with the development of copolymers of ethylene and 2-norbomene by Hoechst and Mitsui using metallocene technology developed by Hoechst. The product is marketed as Topas by Ticona. By adjustment of the monomer ratios polymers with a wide range of Tg values may be obtained including materials that are of potential interest as thermoplastic elastomers. This section considers only thermoplastic materials, cyclo-olefins of interest as elastomers are considered further in Section 11.10. 

There have been other approaches to obtaining rubber/metal adhesion besides primers or additives consisting of phenolics or epoxies plus halogenated elastomers. For example, carboxylated polymers (olefins and diolefins copolymerized with acrylic acid monomers) have shown excellent adhesion to metals. Very little carboxyl is necessary, and polymers with carboxyl contents as low as 0.1% show good adhesion when laminated to bare steel. When these materials possess... 

Ruorocarbon elastomers are convemently divided mto three groups (1) the most widely used group of copolymers of VDF and one or two perfluoroolefins, (2) a less widely used group based on TFE and simple hydrocarbon olefins, and (3) a much smaller group compnsmg copolymers of TFE and jierfluoroolefms [/, 7, 30]... 

Ethylene reacts by addition to many inexpensive reagents such as water, chlorine, hydrogen chloride, and oxygen to produce valuable chemicals. It can be initiated by free radicals or by coordination catalysts to produce polyethylene, the largest-volume thermoplastic polymer. It can also be copolymerized with other olefins producing polymers with improved properties. Eor example, when ethylene is polymerized with propylene, a thermoplastic elastomer is obtained. Eigure 7-1 illustrates the most important chemicals based on ethylene. 

Obviously, there exists severe interplastics competition, e.g. PP vs. ABS, clarified PP vs. PS, PA, PVC, HDPE and PS (Table 10.7). A wide range of cross-linked and thermoplastic elastomer applications, from footware to automotive parts and toothbrushes, are adopting new metallocene-catalysed polyolefin elastomers (POEs). These low-density copolymers of ethylene and octene were first accepted as impact modifiers for TPOs, but now displace EPDM, (foamed) EVA, flexible PVC, and olefinic thermoplastic vulcanisates (TPVs). Interpolymer competition may also result from... 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

---