Chap._300025 - 3.5 Ethylene-propylene Rubber (EPDM),...

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Unformatted text preview: 3.5 Ethylene-propylene Rubber (EPDM), Polyisobutylene (Butyl) Rubber and Relative Low Molecular Weight EPR, PIB and PAO Materials The aliphatic hydrocarbon polymers are soft in nature due to very weak interpolymer interaction. The prevention of polymer chain crystallization by incorporating comonomer units can result in the material with elastic properties with low Tg. * EPR and EPDM EPDM EPR Ziegler-Natta or Metallocene catalyst CH 3 + + Diene CH 2 =CH CH 2 =CH 2 x: 50-60% y: 35-45% z: 1 -8% CH 3 CH 5-ethylidene-2- norbornene (ENB) CH 3 CH CH CH 2 CH 2 =CH Dienes: 1,4 hexadeien z y y x x CH 3 CH 3-(CH 2-CH 2 ) -(CH 2-CH) - -(CH 2-CH 2 ) -(CH 2-CH) -(diene) - At the present time, these materials are prepared exclusively by transition metal (Ziegler-Natta and metallocene) coordination polymerization. Generally, the solution processes are preferred in which a soluble catalyst system is used and the polymer remains in solution rather than form a slurry. A common soluble catalyst systems favor the formation of amorphous atactic polymers and lead to narrower...
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This note was uploaded on 10/16/2010 for the course MATSE 441 taught by Professor Chung,tze-chiang during the Fall '10 term at Pennsylvania State University, University Park.

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