Ethene- propene-diene elastomers

ACRONYMS, ALTERNATIVE NAME EP, EPM, EPR (as Copolymer), EPDM (contains a third monomer, which provides up to 10 weight % of an olefin site for cross-linking), ethene-propene-diene elastomers. 

Processes of ethene/a-olefin copolymerization are of great practical importance. Copolymerization of ethene with small amounts of highest a-olefins (1-butene, 1 -hexene, 1 -octene) allows one to produce linear low density polyethylene (LLDPE), which is one of the most widely used large-scale polyolefin products. Polypropylene, modified with small amounts of ethene, exhibits higher impact strength compared to isotactic homopolypropylene. Copolymerization of propene with large amounts of ethene and terpolymerization of ethene/propene/diene result in amorphous elastomer materials (rubbers) [103]. 

Mw/M = 2, highly linear Copolymerization random distribution, LLDPE co-monomers propene, 1-butene, 1-octene Elastomers, Terpolymers of Ethene, Propene and Diene low transition metal concentration in the polymer, narrow molecular weight distribution Polymerization to ... 

With higher 1-octene content they show that elastic properties polyolefin elastomers (POE) are formed [201]. EPDM is a commercially important synthetic rubber. The dienes as terpolymers are curable with sulfur. This rubber shows a higher growth rate than the other synthetic rubbers [202]. The outstanding property of ethene-propene rubber is its weather resistance since it has no double bonds in the backbone of the polymer chain and thus is less sensitive to oxygen and ozone. Other excellent properties of this rubber are its resistance to acids and alkalis, its electrical properties, and its low-temperature performance [203]. 

Of great industrial interest are the copolymers of ethene and propene with a molar ratio of 1/0.5, up to 1/2. These EP-polymers show elastic properties and, together with 2-5 wt% of dienes as third monomers, they are used as elastomers (EPDM). Since they have no double bonds in the backbone of the polymer, they are less sensitive to oxidation reactions. As dienes, ethylidenenorbomene, 1,4-hexadiene, and dicyclopentadiene are used. In most technical processes for the production of EP and EPDM rubber in the past, soluble or highly disposed vanadium components are used [69]. Similar elastomers can be obtained with metallocene/MAO catalysts by a much higher activity which are less colored [70-72]. The regiospecificity of the metallocene catalysts toward propene leads exclusively to the formation of head-to-tail enchainments. The ethylidenenor-bornene polymerizes via vinyl polymerization of the cyclic double bond and the tendency to branching is low. The molecular weight distribution of about 2 is narrow [73]. 

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