Characterisation of the scratch deformation mechanisms for poly(methvlmethacrylate) using surface optical reflectivity

Abstract

A novel technique using surface local optical reflectivity measurements for characterising the modes of surface mechanical damage of polymers is described. The technique utilises the sensed laser reflectivity of polymer surfaces, after damage, as a means of measuring the relative extent of brittle and plastic deformation modes for polymers. The polymeric surface used in this paper is a commercial poly(methylmethacrylate). The surface damage is produced by scratching with rigid conical indenters under different contact conditions of strain and load. The results show that the local optical reflectivity of a surface depends upon the topography of the surfaces, which varies for different modes of deformation. The reflectivity of a brittle fractured surface is significantly lower in comparison with that for a plastically deformed surface.