Abrasive wear and craze breakdown in polystyrene

Abstract

The role of craze breakdown during the fracture process of abrasive wear in glassy polystyrene was investigated. At first, the wear resistance, γ_w, was compared with the craze breakdown strain as a function of molecular weight and diluent concentration. It was found that γ_w increases with molecular weight and decreases with the diluent concentration. Although craze breakdown strain also increases with molecular weight and decreases with the diluent concentration, the wear data do not converge into a single curve in a plot against the craze breakdown strain. Selected specimens were then studied by micro-indentation and micro-scratching experiments. An analysis of the scratch patterns and contact load at the polymer surface indicated that a critical stress criterion, rather than a critical strain criterion, may be suitable for the onset of the failure process in brittle polymer wear. With this criterion, the critical load for crack opening, τ_c, can be related to the craze breakdown strain and Young's modulus, and the observed deviation between the craze breakdown strain and γ_w can be explained.