Modification of Properties of Composites Based on Ultrahigh Molecular Weight Polyethylene by Creating Two-Layer Coatings with Low Molecular Weight Polyethylene on Filler Particles: Effect of Composition of Two-Layer Coatings on the Structure and Properties of Composites

Abstract

Composite materials with a two-layer coating consisting of ultrahigh molecular weight PE and a lower molecular weight PE are synthesized on the surface of filler particles (Al₂O₃/ultrahigh molecular weight PE/lower molecular weight PE) using the polymerization filling technique by the sequential two-step polymerization of ethylene. In the composites, the ratio ultrahigh molecular weight PE : lower molecular weight PE (polyethylene) is varied with the molecular weight of PE being constant or the molecular weight of PE is varied with the ratio ultrahigh molecular weight PE : lower molecular weight PE being constant. In this case, the lower molecular weight PE is the external layer on the surface of composite particles, while the ultrahigh molecular weight PE occurs directly on the surface of filler particles. In both cases, with an increase in the fraction of polyethylene in the two-layer coating in pressed composites, the degree of crystallinity increases and the lamella parameters change. The mobility of polymer chains in the intercrystalline amorphous layer alters. Creation of two-layer coatings ultrahigh molecular weight PE/lower molecular weight PE allows modification of the deformation–strength properties of the composites. An increase in the content of polyethylene in the composites is accompanied by a considerable increase in the elongation at break and the elastic modulus of the composites while the breaking stress decreases.