Polymerization Kinetics and Modeling of Solution PE Process with Metallocene Catalysts

Abstract

Polymerization methods of ethylene include the slurry, solution, and gas phase processes. The solution process for PE not only allows the operation temperature to reach as high as 300°C, but also produces special grade polymers particularly for ultra-low density polyethylene (PE). This study investigates polymerization conditions and kinetics. The commercial constrained geometry catalyst was used for ethylene polymerization. The kinetic studies were conducted for metallocene type polymerization, including catalyst activation, initiation, chain propagation, chain transfer, and termination steps. In addition, kinetic constants were calculated for the polymerization model. Calculation results of catalyst activity and molecular weight were compared with experimental results, indicating their good correlation. Moreover, the conventional polymerization was modified to accurately predict the molecular weight behaviors under various reaction conditions. Exactly how solvent type, reaction temperature, pressure, catalyst concentration, and cocatalyst ratio affect catalyst activity and molecular weight of polymer was also discussed.