Variation of molecular weight distribution (MWD) and short chain branching distribution (SCBD) of ethylene/1-hexene copolymers produced with different in-situ supported metallocene catalysts

摘要

Copolymerization of ethylene and 1-hexene was carried out with different catalysts: homogeneous Et[Ind](2)ZrCl2, Cp2HfCl2 and [(C5Me4)SiMe2N(tert-Bu)]TiCl2, the corresponding in-situ supported metallocenes catalysts (mixtures of Et[Ind](2)ZrCl2 and Cp2HfCl2, and Et[Ind](2)ZrCl2 and [(C5Me4)SiMe2N(tert-Bu)]TiCl2). Carbon-13 nuclear magnetic resonance spectroscopy (C-13 NMR), gel permeation chromatography (GPC) and crystallization analysis fractionation (CRYSTAF) studies showed that, compared to the corresponding homogeneous metallocenes, in-situ supported metallocenes produced polymers having different 1-hexene fractions, molecular weight distributions (MWD) and short chain branching distributions (SCBD). It was also demonstrated that polymers with broader MWD and SCBD can be produced by combining two different in-situ supported metallocenes. [References: 18]