The influence of the transition metal and the heteroatomic- bridge on the action of metallocene/methyl aluminoxane catalysts in ethylene polymerization and on the properties of the polymer

摘要

This work reports a comparative study of the catalytic behaviour for a series of metallocenes derived from Ti, Zr, Hf and Nb, which after activation with methylaluminoxane can polymerize ethylene. Results show that the Zr metallocene with a —(CH_3)_2Si— bridge presents the highest activity, and the metallocenes based on Hf and Nb do not show any significant activity under the tested conditions.