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Copolymerization of ethylene and propylene catalyzed by magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts

Research paper by Tao Jiang, Hong-xia Chen, Chen-gang Cao, Guo-liang Mao, Wei Du, Deng-fei Wang

Indexed on: 08 Apr '11Published on: 08 Apr '11Published in: Chinese Journal of Polymer Science



Abstract

Magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts with di-i-butyl phthalate as internal donor for copolymerization of ethylene and propylene were prepared. The effects of reaction temperature, ethylene/propylene molar ratio, aluminium/vanadium (Al/V) molar ratio and titanium/vanadium molar ratio on the catalytic activity were investigated. The molecular weight, molecular weight distribution, sequence composition and crystallinity of the products were measured by gel permeation chromatography, 13C-NMR and differential scanning calorimetry analysis, respectively. In comparison to the vanadium and titanium catalysts, the bimetallic catalyst showed higher catalytic activity and better copolymerization performance. The obtained ethylene/propylene copolymers have high molecular weight (105), broad molecular weight distribution, high propylene content with random or short blocked sequence structures (rErP = 1.919), low melting temperatures and low crystallinities (Xc < 20%).