Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal

Abstract

Catalytic systems containing TiCl 4 or TiCl 3 , THF, organomagnesium (n-Bu 2 Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8-7.8) × 10 6 Da and desirable morphology, suitable for modern methods of polymer processing-the solvent-free solid-state processing of superhigh-strength (tensile strength up to 2.1 GPa) and high-modulus (elastic modulus up to 125 GPa) oriented films and film tapes. The impacts of a THF additive, the oxidation state of the titanium atom, and the composition and nature of the nontransition organometallic compounds on the formation of catalytic systems for UHMWPE production were evaluated. The results indicate the suitability of individual titanium chloride tetrahydrofuran complex application for the formation of THF-containing catalytic systems. This approach also results in a significant increase in the system catalytic activity and mechanical properties of UHMWPE. The catalysts based on Ti(III) were inferior to systems containing Ti(IV) in productivity but were markedly superior in the mechanical properties of UHMWPE.

Nano-Dispersed Ziegler-Natta Catalysts for 1 μm-Sized Ultra-High Molecular Weight Polyethylene Particles

“…A higher T m value for the nascent form with respect to that for the melt-crystallized form was explained by the difference in crystal topology, where the cooperative melting of several lamellae is required for the nascent form to adopt the random coil state (Rastogi et al, 2007 ). The crystallinity ( X c ) and the crystallization temperature ( T c ) for all of the samples were found to be in a similar range, and these values are typical for UHMWPE produced by Ziegler-Natta-type catalysts (Table 4 ; Joo et al, 2000 ; Schaller et al, 2015 ; Li et al, 2018 ; Tuskaev et al, 2018 ).…”

Unprecedented Mechanical Properties in Linear UHMWPE Using a Heterogeneous Catalytic System

“…The resulting polymer should be suitable for uniaxial and biaxial solid-state processing and is expected to match the mechanical properties of the homogeneous catalysis counterpart. Although the synthesis of UHMWPE using a heterogeneous catalytic system is not new, ,− the low entangled state that can lead to properties equivalent to those of the homogeneous catalytic system has not been reported yet. Below, experimental findings for the synthesis of UHMWPE using heterogeneous catalytic systems are recalled.…”

A Novel Ziegler–Natta-Type Catalytic System—TiCl4/2,2′-Dimethoxy-1,1′-Binaphthalene/Et3Al2Cl3/Bu2Mg for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solvent-Free Processing

“…Unfortunately, we have not been able to determine MMD to confirm this assumption but, from the results obtained in this work, it follows that the activity of the system with a diether ligand, ceteris paribus, more than twice exceeds the activity of the system based on TiCl 4 (thf) 2 . The mechanical characteristics of the oriented UHMWPE film tapes obtained in this paper also exceed those obtained with the {TiCl 4 –THF–Bu 2 Mg–Et 3 Al 2 Cl 3 } system [19], although the melting points, the degrees of crystallinity, and the molecular masses remain close to each other in both cases.…”

“…In the first approximation, systems based on TiCl 4 complexes with simple cyclic ethers, for example, TiCl 4 (THF) 2 and TiCl 3 (THF) 3 , can be classified as post-metallocene catalysts. These complexes, in the presence of organomagnesium and organoaluminum compounds, are moderately active in the polymerization of ethylene, and lead to the formation of UHMWPE powders which can be processed by the solid-phase method [17,18,19]. However, the organic ligands in these complexes can occupy any of the six sites in the octahedron and, thereby, produce a certain set of active sites upon activation.…”