Effects of residual and external alkylaluminum on the synthesis of syndiotactic polystyrene with cyclopentadienyltitanium tribenzyloxide–methylaluminoxane catalyst
✍ Scribed by Qing Wu; Qinghai Gao; Shangan Lin
- Book ID
- 101257554
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 106 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
The effects of residual trimethylaluminum (TMA) in methylaluminoxane (MAO) and external alkylaluminum (AlR 3 ) on styrene syndiotactic polymerization with CpTi(OBz) 3 as a catalyst precursor have been investigated by comparison of the polymerizations using a series of MAOs containing various amounts of residual TMA. The results indicated that the residual TMA plays a deciding role in the reduction of Ti and promotes formation of the active centers for styrene polymerization. The variations in the catalytic activity and molecular weight of the polymer caused by additions of external AlR 3 , AlMe 3 , AlEt 3 , Al(i-Bu) 3 , and AlEt 2 Cl, into the catalyst systems are quite different, depending the properties of MAO used and the type of the external AlR 3 . It was found that there is an optimum range of concentration ratio of the free AlR 3 , including the residual TMA and external AlR 3 , to the total Al compounds, 25-35 mol %, for maximum catalytic activities. The catalytic activities decrease at the ratios either above or below the range.