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Comparative Study Of Ethylene Polymerization: Using Different Ziegler-Natta Catalysts On An Optimal Condition Obtained By Experimental Design

Mohammad Najafi, Vahid Haddadi-Asl

Various parameters including temperature, pressure, and Al/Ti molar ratio were used to evaluate the polymerization of ethylene using an L27 taguchi experimental design. Response surface method was employed to analyze the catalyst activity and polymerization yield. The results reveal that polymerization yield and catalyst activity are increased by pressure and Al/Ti molar ratio. However, raising temperature results in a decrease in both above-mentioned responses. According to results obtained in this work, pressure and temperature have synergistic effects on both polymerization yield and catalyst activity. A synthesized and two commercial catalysts were used to consider the effect of different catalysts on the polymer properties. The downward trend of catalyst activity in the presence of hydrogen can be easily seen for all the catalysts. Despite a decrease in weight- and number- average molecular weight in the presence of hydrogen, the polydipersity index remains approximately unchanged. The SEM results clearly show the various morphologies of the obtained polyethylenes, which are referred to the morphologies of the catalysts used.