Exploring bimodal HDPE synthesis using single- and dual-site metallocene catalysts: a comprehensive review of the Monte Carlo method and AI-based approaches

Abstract

The alteration of the molecular weight distribution (MWD) in high-density polyethylenes (HDPEs) can effectively address processing challenges. However, widening the MWD may have an adverse effect on the mechanical properties. To overcome this, the generation of a bimodal MWD involving low and high molecular weight polymers simultaneously is preferred. Catalytic polymerization and macromolecular engineering design offer viable approaches to achieve this objective. This study explores various production methods, including gas phase, slurry, and solution processes, for synthesizing HDPE with bimodal MWD. It investigates critical variables such as pressure, temperature, initial reactant concentrations (monomer, co-monomer, hydrogen), as well as the utilization of single- and dual-site metallocene catalysts and co-catalysts, which significantly impact the microstructure of bimodal HDPE. In addition, a comprehensive examination of simulation approaches for HDPE synthesis with bimodal MWD is presented, employing deterministic and stochastic methodologies such as moment equations, Monte Carlo simulations, and artificial intelligence (AI) techniques. Detailed insight is provided regarding the simulation algorithms specifically developed for ethylene copolymerization with various co-monomers. A comparative analysis of the advantages and disadvantages of each method is conducted, along with a discussion on the potential application of these methods in future research endeavors.