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, TiCl 4 anchored on MgCl 2 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.

Novel SiO2‐Supported Chromium Oxide/Chromocene Dual Site Catalysts for Synthesis of Bimodal UHMWPE/HDPE in Reactor Alloys

“…Most of the companies concentrated on the Titanium‐based Ziegler–Natta catalyst system. [ 6 ] Attributed to the high activity, Ziegler–Natta catalyst have been developed till now. Modified heterogeneous Ziegler–Natta‐type catalysts were the most important system to synthesize UHMWPE with improved entanglement and mechanical properties.…”

The First Vanadium-Oxide-Based UHMWPE Catalyst Supported on Chemically Modified Silica Gel

“…Afterward, Allied Chemical Corp. became the first company to industrialize UHMWPE, then Hoechst, Hercules, and Mitsui Petrochemical followed, and most of the catalysts used were titanium‐based Ziegler–Natta (ZN) catalysts. As a matter of fact, more than two‐thirds of UHMWPE is still being produced with ZN catalysts . UHMWPE has very similar chain structure to HDPE, but with much longer chain length, so that some ZN catalysts for HDPE, if being modified properly, could also be possibly used as catalysts for UHMWPE.…”

“…As a matter of fact, more than two-thirds of UHMWPE is still being produced with ZN catalysts. [6] UHMWPE has very similar chain structure to HDPE, but with much longer chain length, so that some ZN catalysts for HDPE, if being modified properly, could also be possibly used as catalysts for UHMWPE. Typically, some TiCl 4 /MgCl 2 catalysts were…”

Remarkable Promotion Effect of Sulfation over the SiO2‐Supported Vanadium‐Oxide‐Based Catalysts for UHMWPE

“…By contrast, the VCl 4 or VOCl 3 ‐based ZN catalysts, though are well known to produce PE with fairly high MW, are rarely reported for the synthesis of UHMWPE, possibly due to their lower activity and stability . Consequently, the commercialized UHMWPE has been mostly produced by TiCl 4 /MgCl 2 ‐based ZN catalysts up to now …”