Microstructure and properties of composite materials based on UHMWPE after mechanical activation

Abstract

In this work microstructure and mechanical properties of UHMWPE composites filled with Al2O3 nanoparticles and microspheres after mechanical activation were studied. Ultra-fine particles of filler are distributed along the boundaries of UHMWPE “grains” and the filling level above 3wt.% leads to forming of a solid layer on the surface of polymer particles, which leads to difficulty in self-diffusion of UHMWPE macromolecules during compaction and, consequently, the change of fracture mechanism. Shock-shear forces during mechanical activation lead to the formation of a metastable monoclinic phase from orthorhombic, breaking chemical bonds. According to proposed model mechanical activation leads to the formation of low molecular weight polymer chains which help to increase the rate of interdiffusion between the borders of the polymer particles and lead to better sintering of UHMWPE particles and higher mechanical properties.