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Atactic polymerization of propylene catalyzed by mono(η5-cyclopentadienyl)titanium tribenzyloxide combined with methylaluminoxane
Authors:Qing Wu  Zhong Ye  Qinghai Gao  Shangan Lin
Abstract:Propylene has been polymerized with mono(η5-cyclopentadienyl)titanium tribenzyloxide activated with methylaluminoxane (MAO). It was found that the content of residual trimethylaluminium (TMA) in MAO has a determinative effect on the polymerization. An excess of TMA in the catalyst system reduces the Ti species to inactive lower valent states. The catalyst system gives medium molecular-weight atactic polypropylene (Mv = 2–7 × 104) with narrow molecular weight distribution (Mw/Mn = 1.4–1.8). The polymer has a stereoirregular structure described by Bernoullian statistics. Statistical analysis of the regiotriad distribution of the polypropylene chains indicates a regioblock microstructure. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2051–2057, 1998
Keywords:propylene polymerization  metallocene catalyst  methylaluminoxane  atactic polypropylene  regioselectivity
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