Effect of the Polymerization Temperature on the Copolymerization of Butadiene and Isoprene Catalyzed by Supported Ziegler-Natta Catalyst

As the most important catalysts in polyolefin industry, heterogeneous TiCl4/MgCl2 Ziegler-Natta ( Heterogeneous Z-N) catalysts activated by alkylaluminium show complex active center structures, which are sensitive to polymerization temperature, polymerization time, type and concentration of alkylaluminium. In this paper, the copolymerization kinetics of butadiene (Bd) and isoprene (Ip) catalyzed by TiCl4/MgCl2-AlEt3 (triethylaluminium) at different polymerization temperatures were studied. It was found that the activity of the copolymerization increased firstly and then decreased with the increase in the polymerization time , and the highest activity was observed at 50 degrees C . The microstructure, the number of active centers, molecular weight and molecular weight distribution of the copolymers studied by proton nuclear magnetic resonance(H-1 NMR) , microcoulometric sulfur spectrometer and gel permeation chromatography (GPC) changed in different ways with the increase in polymerization temperature and polymerization time. The results of this study is helpful 14 further understanding the kinetics and its key influencing factors of conjugated diolefin polymerization catalyzed by heterogeneous Z-N catalysts under different polymerization temperatures.