A comparative Monte Carlo simulation of HDPE synthesis with bimodal molecular weight distribution: evaluating slurry and solution processes using dual-site metallocene catalyst

Abstract

ABSTRACT This research employed Monte Carlo simulation as a computational technique to investigate the copolymerization of ethylene and 1-butene in the presence of hydrogen, utilizing slurry and solution processes. A dual-site metallocene catalyst was utilized to synthesize high-density polyethylene (HDPE) with a bimodal molecular weight distribution (MWD). The solution process accelerated copolymerization rates and hydrogen transfer compared to the slurry. Furthermore, under equivalent conditions, the solution process exhibited a twofold higher level of 1-butene incorporation into copolymer chains. Elevating 1-butene partial pressure by 50% increased weight average molecular weight ( M ¯ w ) of copolymers by 15% in solution process and 5% in slurry process. Increasing 1-butene partial pressure expanded and shifted the bimodal distribution towards higher molecular weights in both processes. Elevated hydrogen partial pressure enhanced peak heights and shifted towards lower molecular weights, with the slurry process showing stronger effects. The solution process had a range of short-chain branching per 1000 carbon atoms (SCB/1000C) (15-40), approximately twice as large as the slurry process. The slurry process resulted in more regular chains with higher crystallinity (68.7%) compared to the solution process (66.4%).