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Study of molecular size in ethylene‐propene copolymerization with zirconocene and hafnocene catalysts
Author(s) -
Naga Naofumi,
Ohbayashi Yoshiaki,
Mizunuma Kooji
Publication year - 1997
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.1997.030180912
Subject(s) - propene , methylaluminoxane , ethylene , copolymer , metallocene , polymer chemistry , polymerization , cyclopentadienyl complex , catalysis , chemistry , chain transfer , materials science , organic chemistry , polymer , radical polymerization
Ethylene‐propene copolymerization was carried out with Cp 2 MCl 2 (Cp = cyclopentadienyl), rac ‐Et(Ind) 2 MCl 2 , rac ‐Me 2 Si(Ind) 2 MCl 2 (Et = ethylene, Me 2 Si = dimethylsilyl, Ind = indenyl, M = Zr or Hf)/methylaluminoxane. In the case of using ansa ‐hafnocenes, the minimum molecular size (extended chain length) of ethylene‐propene copolymer was obtained at about 50 mol‐% of propene content in the copolymer. The polymerization activity decreased with increase of propene feed ratio in non‐bridged non‐specific metallocenes. Higher polymerization activities were observed for the copolymerization compared to ethylene and propene homo‐polymerization with ansa ‐isospecific metallocenes. The factor of molecular size lowering was studied by the chain propagation and chain transfer reaction.