Catalytic Methods for Preparation of Composites Based on Polyethylene and Multilayer Carbon Nanotubes

Abstract

Analytic consideration was focused on the efficiency of methods for the introduction of multilayer carbon nanotubes (MCNT) to polymer composites based on polyethylene (PE) and ultrahigh molecular weight polyethylene (UHMWPE). The methods under consideration were: (1) mechanical mixing of MCNT and a polymer melt; (2) ethylene polymerization over a disperse titanium-magnesium catalyst (TMC) in the presence of MCNT; (3) ethylene polymerization over a TiCl 4 catalyst which was pre-anchored on the MCNT surface. MCNT/PE and MCNT/UHMWPE composites with different MCNT contents (3,5 to 19 wt.%) were prepared at varying the polymerization conditions, and their properties (uniformity of MCNT distribution through the polymer, molecular-mass characteristics, viscosity, fluidity, electrical conductivity) were characterized. The most uniform distribution was shown to achieve when ethylene is polymerized over the catalyst anchored directly to the nanotube surface (method 3). Method 1 is only of limited use in preparation of MCNT/UHMWPE because of the high viscosity of UHMWPE. Practically identical molecular weights are characteristic of polymers are obtained upon ethylene polymerization over the TMC catalysts and over catalysts anchored on MCNT. The proper choice of the catalytic system and polymerization conditions makes it possible to synthesize MCNT/PE composites with the required polymer properties.