COPOLYMERIZATION OF ETHYLENE AND PROPYLENE CATALYZED BY MAGNESIUM CHLORIDE SUPPORTED VANADIUM/TITANIUM BIMETALLIC ZIEGLER-NATTA CATALYSTS

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,;C-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 （10;）,broad molecular weight distribution,high propylene content with random or short blocked sequence structures （r;r;=1.919）,low melting temperatures and low crystallinities（X;<20%）.