Synthesis of Ultrahigh Molecular Weight Polyethylene Using Traditional Heterogeneous Ziegler−Natta Catalyst Systems

Abstract

Ultrahigh molecular weight polyethylene was synthesized from traditional Ziegler−Natta type catalysts (ZN), namely, TiCl4 anchored on MgCl2 support. This, upon activation with AlRR′2 (where R, R′ = isoprenyl or isobutyl), gave precatalysts (C-2 to C-5) having 16, 21, 25, and 32% trivalent titanium, respectively. The reduction in oxidation states also accompanies the reduction in particle size of the catalysts, which in turn gets reflected in the resulting polymer properties under specified operating conditions. We have demonstrated the effect of process conditions that can surmount the catalyst dependency over the polymer characteristics, and hence, it can result in polymer with consistent polymer properties, which is an important need of the polymer industries. The polymer characteristics such as particle size distribution, average particle size, bulk density, reduced specific viscosity, and concentration of fine and coarse particles were determined and were dependent on various process parameters. Under identical reaction conditions, the polymerization with larger scale yield polymer with different characteristics. The fine-tuning of process conditions yielded polymer with consistent quality.