Ethylene-propylene-diene terpolymers unsaturation

Improved ABS-similar resins can be obtained by grafting SAN onto ethylene-propylene-diene terpolymers (EPDMs) which contain, usually, a much lower degree of unsaturation than polybutadiene, thus achieving hi er thermal-oxidative resis-tance However, only EPDMs containing a sufficient amount (7—10 double bonds per 1,000 C atons) of reactive unsaturations, e.g. ethylidene or isopropylidene groups, display a grafting efficiency sufiident to bring about compatibility of the ssy i se with the rubbery one and hence satisfactory final properties. 

These polyolefin rubbers are produced in two main types the saturated co-polymers, ethylene propylene rubber (EPM), and the unsaturated ethylene-propylene diene terpolymer (EPDM). The monomers are co-polymerised in ziegler natta type catalysts. The EPDM types are capable of sulfur vulcanisation as they contain, in addition to olefins, a non coagulated diene as the third monomer. 

Ethylene-propylene-diene terpolymer (EPDM) is an unsaturated PO rubber with wide applications. Several researchers [136,160,317] reported the results of investigations on... 

Fourthly, avoid the use of very high cavity temperatures. These are not generally necessary to obtain short cure times, and certainly speed the rates at which residues are deposited. For natural rubber aim at a cavity temperature of 165 °C. For synthetic rubbers with low levels of unsaturation such as ethylene-propylene diene terpolymer this will need to be increased to 180 °C. The cavity temperature is usually 10 °C to 15 °C below the set point of the platens. 

Determination of Unsaturation in Ethylene-Propylene-Diene Terpolymers... 

This technique has found the following applications in addition to those discussed in Sections 10.1 (resin cure studies on phenol urethane compositions) [65], 12.2 (photopolymer studies [66-68]), and 13.3 (phase transitions in PE) [66], Chapter 15 (viscoelastic and rheological properties), and Section 16.4 (heat deflection temperatures) epoxy resin-amine system [67], cured acrylate-terminated unsaturated copolymers [68], PE and PP foam [69], ethylene-propylene-diene terpolymers [70], natural rubbers [71, 72], polyester-based clear coat resins [73], polyvinyl esters and unsaturated polyester resins [74], polyimide-clay nanocomposites [75], polyether sulfone-styrene-acrylonitrile, PS-polymethyl methacrylate (PMMA) blends and PS-polytetrafluoroethylene PMMA copolymers [76], cyanate ester resin-carbon fibre composites [77], polycyanate epoxy resins [78], and styrenic copolymers [79]. 

Formation of a strong interfacial layer is the key factor of the mechanism describing retardation of ozone degradation of a diene rubber by elastomer additives with a low degree of unsaturation [1-4]. The effect of comonomer ratio in ethylene-propylene-diene terpolymers (EPDMs) and stereoregularity of propylene units on the interfacial interaction and the amount of crosslinks in ihe interfacial layer was considered for heterophase crosslinked blends with butadiene-acrylonitrile mbbers (BNRs) of different polarities. 

The iodine monochloride method has been used for various polymers. These polymers include those which are highly unsaturated, such as polybutadiene and polyisoprene [91-94] and polymers having low unsaturation such as butyl rubber [95], and ethylene-propylene-diene terpolymers. Considerable work has been done investigating the side reactions of iodine monochloride with different polymers. [95]. These side reactions are substitution and splitting out rather than the desired addition reaction. 

IR spectroscopy and pyrolysis gas chromatography have been used for the determination of unsaturation in ethylene-propylene-diene terpolymers [88]. Determination of extinction coefficients for the various terpolymers is required for quantitative work. 

NMR spectroscopy has been used to determine unsaturation in acrylonitrile-butadiene-styrene terpolymers [107], ethylene-propylene-diene terpolymers [108] and 1,2-polybutadiene [105]. 

Polymerization of ethylene and propylene results in a saturated copolymer. In order to vulcanize this rubber, some unsaturation has to be introduced. This is commonly done by adding a few percent of non-conjugated diene (termonomer) such as dicyclopentadiene, 1,4-hexadiene, or ethylidene norborene during the polymerization. Since only one of the double bonds of the diene reacts during polymerization, the other is free for vulcanization. The amount of unsaturation left in the ethylene propylene diene terpolymer is of great interest because the vulcanization properties will be affected. 

Copolymerization of ethylene and propylene produces an elastomeric polymer that is virtually inert because of the absence of carbon-carbon double bonds (EPM). Such polymers thus tend to be crossUnked with peroxides or by radiation. To improve the reactivity of ethylene-propylene copolymers, 1-10% of a third monomer can be added to give a terpolymer or ethylene-propylene-diene monomer (EPDM). The primary diene monomers used in EPDM are 1,4-hexadiene, dicyclopentadiene, and ethyUdene norbomene. Introduction of an unsaturated monomer such as ethylidene norbomene will enable use of sulfur-based crosslinking systems. 

Ethylene-propylene rubber is a synthetic hydrocarbon-based rubber made either from ethylene-propylene diene monomer or ethylene-propylene terpolymer. These monomers are combined in such a manner as to produce an elastomer with a completely saturated backbone and pendant unsaturation for sulfur vulcanization. As a result of this configuration, vulcanizates of EPDM elastomers are extremely resistant to attack by ozone, oxygen, and weather. 

Organic peroxides are used in the polymer industry as thermal sources of free radicals. They are used primarily to initiate the polymerisation and copolymerisation of vinyl and diene monomers, eg, ethylene, vinyl chloride, styrene, acryUc acid and esters, methacrylic acid and esters, vinyl acetate, acrylonitrile, and butadiene (see Initiators). They ate also used to cute or cross-link resins, eg, unsaturated polyester—styrene blends, thermoplastics such as polyethylene, elastomers such as ethylene—propylene copolymers and terpolymers and ethylene—vinyl acetate copolymer, and mbbets such as siUcone mbbet and styrene-butadiene mbbet. 

EPDM is a terpolymer of ethylene, propylene, and a small amount (<10%) of an unsaturated diene third monomer to provide a cure site. Unlike the elastomers previously discussed, the unsaturation in EPDM is not in the main chain, but it is pendent to the chain. Peroxide cure gives superior aging resistance and low compression set. 

EPDM terpolymer of ethylene, propylene and a diene with the residual unsaturated... 

EPDM - ASTM abbreviation for a terpolymer of ethylene, propylene, and a diene with the residual unsaturated portion of the diene in the side chain. 

EPDM terpolymers of ethylene, propylene, and a small percentage of a non-conjugated diene, which makes the side chains unsaturated. 

Copolymerization of ethylene with propylene results in a random, noncrystalline copolymer that is a chemically inert and rubbery material. EPM is a saturated copolymer that can be cross-linked through the combination of the free radicals generated by peroxides or radiation. To incorporate sites for vulcanization, an unsaturated terpolymer can be prepared from ethylene, propylene, and a small amount (3 to 9%) of a nonconjugated diene (EPDM). The diene is either dicyclopentadiene, ethylidene nor-bomene, or 1,4-hexadiene. The resulting unsaturated terpolymer can be vulcanized by traditional techniques. Each of the termonomers confers different characteristics on the final elastomer. 

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