含稀土的钛系催化剂进行乙烯聚合动力学及ZnCl2调节分子量的研究

以SN-1催化剂进行乙烯常压聚合动力学研究表明,催化剂高效的主要原因是活性中心浓度明显增大、表观活化能△E较低。研究了ZnCl₂对乙烯聚合反应的影响。发现ZnCl₂能有效地降低聚乙烯的分子量,并能显著地提高催化效率,当ZnCl₂浓度过大时,则对聚合反应有抑制作用。

Kinetics of Ethylene Polymerization and Regulation of Molecular Weight with ZnCl_2

The kinetics of the polymerization of ethylene has been studied at normal pressure with the highly active catalyst system TiCl₄,NdCl₃/MgCl₂/Al(C₂H₅)₃. The rate of polymerization V_P,the specific number of active centers C^*] , the propagation rate constant k_P,the activation energy ΔE and the lifetime of growing chain Lwere obtained by a kinetics method for the polymerization of ethylene. The influence of ZnCl₂ on the polymerization of ethylene has been investigated. It has been found that ZnCl₂ is a considerably effective transfer agent. Not only it decreases the molecular weight of polyethylene, but raises the catalytic efficiency notably as well. However, at a higher ZnCl₂ concentration, the rate of polymerization was decreased.