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

Abstract

Copolymerization of ethylene and 1-hexene was carried out with different catalysts: homogeneous Et[Ind] 2 ZrCl 2 , Cp 2 HfCl 2 and [(C 5 Me 4 )SiMe 2 N(tert-Bu)]TiCl 2 , the corresponding in-situ supported metallocenes and combined in-situ supported metallocene catalysts (mixtures of Et[Ind] 2 ZrCl 2 and Cp 2 HfCl 2 , and Et[Ind] 2 ZrCl 2 and (C 5 Me 4 )SiMe 2 N(tert-Bu)]TiCl 4 ). Carbon 13 nuclear magnetic resonance spectroscopy ( 31 C NMR), gel permeation chromatography (GPC) and crystallization analysis fractionation (CRYSTAF) studies showed that, compared is the corresponding homogeneous metallocenes, in-situ supported metallocenes produces 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.