Copolymerization of ethylene and 1-hexene with in-situ supported Et[Ind]2ZrCl2

Abstract

Copolymerization of ethylene and 1-hexene was carried out with different catalysts (homogeneous Et[Ind]2ZrCl2, supported Et[Ind]2ZrCl2 and in-situ supported Et[Ind]2ZrCl2). The novel in-situ supported metallocene catalyst showed higher activity than the corresponding supported metallocene catalyst. 13C NMR, gel permeation chromatography and crystallization analysis fractionation studies showed that the microstructure of ethylene/1-hexene copolymers depends upon catalyst type. At the same polymerization conditions, the relative reactivity of 1-hexene increases in the following order: supported metallocene ≈ in-situ supported metallocene < homogeneous metallocene. The molecular weights of the produced copolymers with the three different catalysts are similar, but the molecular weight distribution of the copolymer made with the in-situ supported metallocene is broader than that of those made with the other catalysts. The short chain branching distribution (SCBD) of the copolymer produced with the in-situ supported metallocene catalyst is the broadest with a shoulder in the high crystallinity range, while the copolymers produced with the homogeneous and supported metallocene catalysts show unimodal SCBD. This may indicate that there are at least two different active species with the in-situ supported metallocene catalyst in the copolymerization of ethylene and 1-hexene.