Investigation of Optimal Condition of Ethylene Polymerization Using a New Three-Metallic High-Performance Ziegler–Natta Catalyst: Experimental Design and Polymer Characterization

Ziegler–Natta (ZN) catalyzed polymerizations have been used for the production of a wide variety of polyolefin with different characteristics and various applications such as polyethylene and polypropylene. In such polymerization processes, different parameters such as polymerization temperature, monomer pressure, and [Al]/[Ti] molar ratio play an important role in conducting a successful polymerization with desired productivity and final product properties. This paper aims to investigate the individual and simultaneous effects of these parameters on the catalyst activity, polymerization yield, and resultant polymer properties. For this purpose, a new three-metallic high-performance ZN catalyst was synthesized for applying in the ethylene polymerization. Response surface methodology (RSM) and an N = 15 Box-Benkhen design were used to analyze the catalyst activity and polymerization yield. The result revealed that catalyst activity and polymerization yield increase by increasing the polymerization pressure and [Al]/[Ti] ratio while increasing polymerization temperature decrease both above-mentioned responses. Optimal polymerization parameters suggested by the program are applied to the polymerization process for obtaining higher catalyst activity and polymerization yield. Kinetic behavior of catalyst also has been investigated through polymerization course. In the final part of the present work, comprehensive characterization of obtained polymer in terms of thermo-physical and mechanical properties have been conducted. The result revealed that the obtained polymer is an ultrahigh molecular weight polyethylene.