双组分茂金属催化剂催化乙烯聚合的研究

选择能形成支链的不对称桥联茂金属化合物Me2 C(Cp) (Ind) ]ZrCl2 和非桥联的不同结构的茂金属化合物二氯二 (烯基取代环戊二烯 )锆如 ( Cp) 2 ZrCl2 ,(Cp) 2 ZrCl2 和 (Cp) 2 ZrCl2 ,以MAO为助催化剂 ,分别组成三组双组分茂金属催化剂的催化体系 ,催化乙烯聚合 .结果表明 ,两类催化剂组成的双组分茂金属催化体系催化乙烯聚合能得到支化的宽分子量分布的聚乙烯 ;聚合温度和改变两种茂金属催化剂的摩尔比对催化活性和分子量有很大影响 .因此可以利用改变双组分茂金属催化剂的摩尔比例和聚合温度来调控聚合物的分子量和分子量分布 .改变两种茂金属催化剂的摩尔比和聚合温度也能使聚合物的结晶度发生改变

ETHYLENE POLYMERIZATION CATALYZED BY USING TWO-COMPONENT METALLOCENE CATALYSTS

Polyethylene with broad molecular weight distribution can be obtained by using catalytic systems consisting of two or more catalyst components. An asymmetrically bridged metallocene compound (CH 3) 2C(η-C 5H 4)(η-C 9H 6)]ZrCl 2 and different unbridged metallocene compounds( Cp) 2ZrCl 2,( Cp) 2ZrCl 2 and ( ZJZS;ZX;LX,Y] Cp) 2ZrCl 2 were used to constitute three catalytic systems cocatalyzed with MAO for ethylene polymerization.Polyethylene with short chain branch and broad molecular weight distribution was obtained.By changing the molar ratio of two-component metallocene catalysts and polymerization temperature,the activity of the ethylene polymerization and the molecular weight and molecular weight distribution of the resultant polyethylene were investigated.The molecular weight and molecular weight distribution of polyethylene were determined by viscometry and GPC.The melt point and crystallinity of polyethylene samples were determined by DSC.The results showed that the molar ratio and polymerization temperature had important effect on the activity and molecular weight.The results indicated that it was possible to tailor molecular weight and molecular weight distribution by changing the molar ratio of the two-component metallocene catalysts and polymerization temperature in ethylene polymerization with two-component metallocene catalyst systems.