Ethylene propylene 1,4 hexadiene

Polymer alloys comprised 20-30 wt% PP, 25-35 wt% uncross-linked elastomeric ethylene-propylene-1,4-hexadiene, EPDM (60-80 wt% ethylene), 30-50 wt% ionomer, and 2-3 wt% ethylene/ -butyl acrylate/ glycidyl methacrylate, EBA-GMA. The blends were used in applications where a wide temperature range and abrasive conditions were encountered... 

Figures 3.4 Ethylene propylene 1,4 hexadiene and EPDM with ENB...

Thermoplastic elastomers Ethylene-propylene-1,4-hexadiene terpolymer Japan 19,351 1978 DuPont... 

The amount of unsaturation introduced is generally within the range 2-15 double bonds per 1000 carbon atoms, distributed randomly throughout the polymer. The structure of an ethylene-propylene-1,4-hexadiene terpolymer might therefore be represented as follows ... 

Nordel [Du Pont], TM for an elastomer based on an ethylene-propylene-hexadiene terpo-lymer, sulfur curable. 

Ethylene—Propylene Rubber. Ethylene and propjiene copolymerize to produce a wide range of elastomeric and thermoplastic products. Often a third monomer such dicyclopentadiene, hexadiene, or ethylene norbomene is incorporated at 2—12% into the polymer backbone and leads to the designation ethylene—propylene—diene monomer (EPDM) mbber (see Elastomers, synthetic-ethylene-propylene-diene rubber). The third monomer introduces sites of unsaturation that allow vulcanization by conventional sulfur cures. At high levels of third monomer it is possible to achieve cure rates that are equivalent to conventional mbbers such as SBR and PBD. Ethylene—propylene mbber (EPR) requires peroxide vulcanization. 

The simplest diene that satisfies this requirement is 1,4-hexadiene, and indeed it has been adopted as the cure site monomer in commercial ethylene-propylene-diene rubber. Because 1,4-hexadiene exists in both trans and cis configurations, significant amounts of work have been devoted to find ways to control the selectivity of the catalysts for one of the isomers over the other. 

Commercial grades of ethylene-propylene copolymers (EPR) contain 60-75 mol% of ethylene to minimize crystallization. The addition of a third monomer, such as 1,4-hexadiene, dicyclopentadiene, or 5-ethylidene-2-norbornene, produces generally amorphous faster-curing elastomers. A large number of such terpolymers, referred to as EPDM, is available commercially. Their properties, performance, and response to radiation vary considerably depending on macrostructure, ethylene/propylene ratio, as well as on the type, amount, and distribution of the third monomer. 

Codimerization of ethylene and 1,3-butadiene is also of commercial significance since the product 1,4-hexadiene is used as a comonomer in the manufacture of ethylene-propylene-diene elastomers. Rhodium and nickel catalysts are used since they are the most active and selective, bringing about the formation of the required... 

With larger amount of propylene a random copolymer known as ethylene-propylene-monomer (EPM) copolymer is formed, which is a useful elastomer with easy processability and improved optical properties.208,449 Copolymerization of ethylene and propylene with a nonconjugated diene [EPDM or ethylene-propylene-diene-monomer copolymer] introduces unsaturation into the polymer structure, allowing the further improvement of physical properties by crosslinking (sulfur vulcanization) 443,450 Only three dienes are employed commercially in EPDM manufacture dicyclopentadiene, 1,4-hexadiene, and the most extensively used 5-ethylidene-2-norbomene. 

The effect of nucleophilic dienes on the copolymerization of ethylene and propylene has been reported by Gladding, Fisher and Collette (88). Table 8 shows that 1.4-hexadiene decreased the tendency for propylene to enter into the ethylene-propylene terpolymer, produced by a triisobutyl aluminum-vanadium oxychloride catalyst. 

HD. See Hexadiene. - [ELASTOMERS,SYNTHETIC - ETHYLENE-PROPYLENE-DIENE RUBBER] (Vol 8)... 

Random ethylene/propylene copolymers are amorphous and represent an interesting class of synthetic elastomers. The introduction of double bonds, useful for sulphur vulcanisation in the copolymer, can be achieved by copolymerisation of ethylene and propylene with non-conjugated dienes containing only one double bond capable of insertion for instance, 1,4-hexadiene, dicy-clopentadiene and 5-ethylidene-2-norbornene (endocyclic double bond)... 

Explain why 1,4-hexadiene, but not 1,5-hexadiene, is used for obtaining ethylene/ propylene/non-conjugated diene vulcanisable terpolymers. 

Butadiene could also be trimerized to give cyclododecatriene. The trimer is again used by Hulls to manufacture nylon 12 and Vestamid . The codimerization of butadiene and ethylene is used by DuPont to manufacture 1,4-hexadiene, one of the monomers of EPDM (ethylene, propylene, diene, monomers) rubber. The role of the diene monomer in EPDM rubber is to provide with two double bonds of different reactivities. The more reactive, terminal double bond takes part in the polymerization with ethylene and propylene. The less reactive internal one is used later on for cross-linking. These important catalytic reactions are shown in Fig. 7.6. 

Hexadiene is utilized as a third co-monomer in ethylene/propylene elastomers. While the terminal double bond is incorporated into the polymeric chain, the internal one is not and can be cross-linked (vulcanized) to confer... 

Examples of terpolymerizations have also been reported ethylene/styrene/l,5-hexadiene,561 ethylene/propylene/... 

Ethylene/propylene co-polymers (usually called EPRs for ethylene-propylene rubbers, or EPMs for ethylene-propylene monomers) are amorphous polyolefins when the propylene content is in the range 30-70%. Despite the typical unreactivity of saturated polyolefins, ethylene-rich EP co-polymers can be made highly elastic by radical cross-linking, but in order to make the rubber vulcanizable , a diene (5-ethylidene-2-norbornene, 1,4-hexadiene, or dicyclopentadiene) is added, which leaves one unreacted double bond available for subsequent cross-linking. These latter materials are called EPDMs (for ethylene-propylene-diene monomers). 

The cyclo-co-polymerization of 1,5-hexadiene and ethylene catalyzed by Cj-symmetric ansa-zirconocenes gives access to alternating co-polymers,1036and lends further supporting evidence for the proposed mechanism of alternation in ethylene/propylene co-polymerization.575... 

Ethylene/propylene/l,4-hexadiene with an ethylene/propylene ratio of 4.5 mol%... 

The photoinitiated crosslinking of three ethylene-propylene-diene copolymers (EPDM elastomers) has been investigated in a series of studies > > >9. Commercial EPDM samples were used containing the following dienes ethylidene-norbomene (ENB), dicydopentadiene (DCPB) and hexadiene (HD). The main photoinitiators used were benzoyl-1-cyclohexanol (PI) from Ciba-Geigy and 2,4,6-trimethyl-benzoyl diphenylphosphineoxide (APO) from BASF, which both are photofragmenting (formulas 3 and 4) ... 

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. 

From other p<%olefins, photocrossiinking of ethylene propylene da omers, copolymerized with dienes such as dicyclopentadiene, 1.4-hexadiene, and 5-ethylidene... 

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. 

EPDM Rubber Sulfur-vulcanizable thermosetting elastomer produced from ethylene, propylene, and a small amount of nonconjugated diene such as hexadiene. Has good weatherability and chemical and heat resistance. Used as impact modifiers and for weather stripping, auto parts, cable insulation, conveyor belts, hoses, and tubing. Also called EPDM. 

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