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Evolution of Molecular Weight and Long Chain Branch Distributions in Olefin–Diene Copolymerization

✍ Scribed by Márcio Nele; João B. P. Soares; José Carlos Pinto

Publisher
John Wiley and Sons
Year
2003
Tongue
English
Weight
219 KB
Volume
12
Category
Article
ISSN
1022-1344

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✦ Synopsis

Abstract

A model for olefin–diene copolymerization and long chain branch formation was developed. The model shows that the number‐average molecular weight and branching density increases linearly with time in a semi‐batch polymerization, while the polydispersity depends on the diene content in the polymer and on the polymerization time. For low diene fractions or low polymerization times, the polydispersity increases linearly with time. For higher diene contents, the polydispersity increases exponentially with polymerization time after a critical polymer concentration is reached. The calculated distributions of branched species indicate that diene content influences the amount of highly branched chains produced in the polymerization, markedly broadening the distribution of molecular weight and leading to gel formation.

Weight distribution of branched species after 30 min of polymerization.

magnified imageWeight distribution of branched species after 30 min of polymerization.

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