Two-Step Ethylene Slurry Polymerization with Magnesium Dichloride-Supported Titanium Catalyst

High-density polyethylene (HDPE) was synthesized using a Ziegler-Natta catalyst in two different ways: one step and two-step processes in a hexane slurry polymerization. The study explored the impact of adding hydrogen as a chain-terminating agent on various properties of the polymer, such as productivity of catalyst, molecular weight distribution variation, melt flow index (MFI) and resin average particle size distribution. The results revealed that increasing hydrogen concentrations led to the production of low-molar mass and high MFI polyethylene in the one-step process. Conversely, decreasing hydrogen concentration and increasing ethylene concentration produced higher molar mass/low MFI polyethylene in the same one-step process. In the two-step process, low-molar mass PE was formed first, followed by high-molar mass PE, resulting in broad molecular weight distribution (MWD). This research provides insights into controlling the molecular weight of polyethylene in slurry polymerization processes, which is significant for industrial polymerization technology.