METALLOCENE POLYETHYLENES WITH BROAD OR BIMODAL MOLECULAR WEIGHT DISTRIBUTION  

作　　者：田军 王佰全 陈寿山 刘宇 黄葆同 

机构地区：[1]Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022, China [2]Nankai University, Tianjin 300071, China

出　　处：《Chinese Journal of Polymer Science》1998年第4期370-376,共7页高分子科学（英文版）

摘　　要：Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.

关 键 词：metallocene polyethylene binuclear titanocenes 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]