Rubber, conjugated diene ethylene-propylene

The discovery by Ziegler that ethylene and propylene can be polymerized with transition-metal salts reduced with trialkyl aluminum gave impetus to investigations of the polymerization of conjugated dienes (7—9). In 1955, synthetic polyisoprene (90—97% tij -l,4) was prepared using two new catalysts. A transition-metal catalyst was developed at B. E. Goodrich (10) and an alkaU metal catalyst was developed at the Ekestone Tke Rubber Co. (11). Both catalysts were used to prepare tij -l,4-polyisoprene on a commercial scale (9—19). 

In order to overcome this drawback, new types of multi-unsaturated hydrocarbon monomers have been synthesized in recent years and their behavior in ethylene-propylene copolymerization has been extensively studied. Such monomers are characterized by the presence of one unconjugated double bond suitable for copolymerization and of a system of two or three conjugated double bonds, the high reactivity of which makes them competitive with conventional diene rubbers in sulfur vulcanization despite their low concentration. 

Atactic poly(methyl methacrylate) Atactic polystyrene Butyl-rubber Chlorinated polyethylene Deuterated high density polyethylene Ethylene butylacrylate Elastomeric copolymer from ethylene and ethyl acrylate Elastomeric terpolymer from ethylene, propylene and a non-conjugated diene Elastomeric ethylene-propylene... 

Triple ethylene-propylene rubbers of SKEP(T) brands contain up to several percents of non-conjugated dienes predominantly dicyclopentadiene (DCPD) and ethylidennorbomene (ENB) as third comonomers [177]. 

The major commercial use of propylene oxide is as a comonomer for copolymerization. The block copolymerization with ethylene oxide produces water-soluble detergents. The copolymerization of propylene oxide with non-conjugated dienes produces sulfur-vulcanizable, oil-resistant elastomers that remain rubber-like at low temperatures. The elastomers obtained by the copolymerization of propylene oxide with allyl glycidyl ether have only poor oil resistance, but have good ozone resistance and remain rubberlike at low temperatures. 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

Polymerisation of ethylene and propylene results in a saturated copolymer. To vulcanise this rubber, some unsaturation must be introduced. This is commonly done by adding a few percent of non-conjugated diene (termonomer) such as dicyclopentadiene, 1,4-hexadiene, or ethylidene norbornene, during polymerisation. Because only one of the double bonds of the diene reacts during polymerisation, the other is free for... 

Composition Maleic anhydride modified ethylene/propylene/ non-conjugated diene elastomer Physical Form Rubber Pellets Specific Gravity 0.85 Total Maleic Anhydride/Acid 0.5%... 

EPDM n Elastomer from ethylene, propylene, and a diene. Abbreviation for Elastomeric Terpolymer from ethylene, propylene, and a conjugated diene. See Ethylene-Propylene Rubber. 

For many years Ziegler-Natta coordination copolymerization of ethylene with propylene and non-conjugated dienes (such as hexa-1,4-diene and 5-ethylidene-2-norbornene) has been used to prepare an important class of rubbers known collectively as EPDM rubbers. More recently, copolymerization of ethylene with small proportions of higher a-olefins (such as but-l-ene, hex-l-ene and oct-l-ene) has become important and is used to prepare a range of copolymers known as linear low-density polyethylenes (LLDPE). 

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