화학공학소재연구정보센터
Polymer, Vol.51, No.21, 4713-4725, 2010
Supported hybrid early and late transition metal catalysts for the synthesis of polyethylene with tailored molecular weight and chemical composition distributions
Supported hybrid catalysts using metallocenes and a nickel diimine catalyst were synthesized and used for ethylene slurry polymerization and ethylene/1-hexene copolymerization. Two types of metallocenes, together with a nickel diimine catalyst were supported onto SiO2 through chemical bonding, and a borate compound was physisorbed for the activation of the catalysts. These supported hybrid catalysts had high catalyst activities and made free-flowing polymer particles. The chemical composition distribution, molecular weight averages and distributions of resultant polymers were controlled by catalyst structure and polymerization conditions such as reaction temperature and the use of a-olefin. According to GPC-IR, C-13 NMR and CEF characterization results of some polymers, more 1-hexene was incorporated in the high molecular weight region, short chain branches were generated by the chain walking mechanism in low molecular weight region. The morphologies of the resulting particles were investigated by SEM. (C) 2010 Elsevier Ltd. All rights reserved.