Synthesis of Metallocene Catalyst for Terpolymerization of Ethylene, Propylene and Diene

The bis (indenyl) zirconium dichloride catalyst was synthesized by a modified method at room temperature. Terpolymerization of ethylene، propylene and diene monomers were carried out using this metallocene catalyst under different conditions of different feed ratios of monomers، co-catalyst/catalyst ratios and polymerization temperatures. Methylaluminoxane (MAO) was used as a co-catalyst. The highest activity of catalyst was obtained at total pressure 4 bar، co-catalyst/catalyst ratio [Al] / [Zr] =600، polymerization temperature 60°C and E/P=67:33 and momomer feed ratio of 1700 kgEPDM/molZrh. The activity of catalyst showed bell-shaped behaviors versus co-catalyst/catalyst ratio ([Al] / [Zr]) and polymerization temperatures. The viscosity-average molecular weight (Mv) of terpolymers increased with increasing total pressure at different feed ratios of monomers. However، the viscosity-average molecular weight of terpolymers decreased at higher co-catalyst/catalyst ratios ([Al] / [Zr]) and higher polymerization temperatures. The increases in propylene and diene monomers in the feed ratios decreased the catalyst activity and viscosity-average molecular weight of terpolymers. The ratio of maximum average rate of terpolymerization to an average rate of terpolymerization at the end of the polymerization (DI) for different terpolymerization conditions was relatively high; an indication of the decay kinetics for this type of metallocene catalyst. Increasing the co-catalyst/catalyst ratio up to [Al] / [Zr] = 500 increased the Et% and ENB% in the final obtained polymers. However، increasing the polymerization temperature، diene and propylene concentrations in the feed ratio decreased the Et% and increased the ENB% contents in the final obtained polymers. Tg of the final terpolymers was between -64 and -52°C. The study on microstructures of some polymer revealed block type of chain microstructures.