胺基取代单茂钛／甲基铝氧烷催化乙烯聚合

Polymerization of ethylene with amidogen substituted mono（η5- cyclopentadienyl） titanium/methyl aluminoxane catalyst

采用胺基取代单茂钛{Cp*TiCl2N[Si(CH3)3]2}与甲基铝氧烷组成的催化体系进行乙烯聚合,得到聚乙烯 (PE)。该体系催化活性在40℃下最高,达78．5 kg,(mol·h)。PE的相对分子质量随聚合温度的下降有明显增大,在 0-60℃时重均分子量为(16-60)×104。对PE的差示扫描量热法及核磁共振碳谱表征结果表明,通过控制不同的聚合条件,PE的熔融温度可以在118-130℃变化。聚合温度和n(Al)/n(Ti)对PE的支化度都有显著影响,PE的支化类型主要为丁基支链。

Polyethylene （PE）was synthesized by catalyzing ethylene with a compound system consisted of Cp＊TiCl2N[Si（CH3）3]2 and methyl aluminoxane. The catalytic activity of the system reached its maximum of 78.5 kg/（mol.h） at temperature of 40℃. The relative molecular mass of the PE resin remarkably went up as the polymerization temperature lowered, e.g. its weight average molecular weight attained （16-60）×10^4 in the temperature range from 0 to 60℃. The characterization of the PE specimen by differential scanning calorimetry and ^13C spectrum of nuclear magnetic resonance spectrometry indicate that the melt temperature of the PE resin can vary in the range of 118-130℃ through controlling polymerization parameters. Both the ratio of Al to Ti and the polymerization temperature can significantly influence the degree of branching of the PE resin. Butyl branched chain substantially represents the major branched structure of the PE so prepared.