Polymer reactions—X thermal pyrolysis of poly(isoprene) |
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Authors: | J.C.W. Chien J.K.Y. Kiang |
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Affiliation: | Materials Research Laboratories, Department of Polymer Science and Engineering, Department of Chemistry, University of Massachusetts, Amherst, MA 01003, U.S.A. |
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Abstract: | Poly(isoprene) (97% cis-1,4 and 3% 3,4) has been pyrolysed in a carrier stream of helium from 315 to 384°. The products were online identified and quantitatively analysed by an interfaced pyrolysis GC peak identification system. The first order rate constant for pyrolysis is 1.1 × 10?2 sec?1 at 384° with an overall activation energy of 41 kcal mol?1. The main products are isoprene and 1-methyl-4-isopropenyl cyclohexene. The dominant initiation process has been shown to be β chain scission leading to two allylic radicals. The former product is derived from an unzipping reaction, the latter together with 1.5-dimethyl-5-vinylcyclohexene are the main C10 products from the allylic radicals. All the other minor products can be account for by simple chain propagation reactions with or without intramolecular hydrogen transfers. |
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