Friction induced plastic deformation of high polymer surfaces

Four standard glassy polymers are subjected to a classical single pass friction test by a spherical glass indenter. The plastic deformation of the polymers surfaces resulting from a single sliding pass was examined by scanning probe microscopy using intermittent contact mode. Debris were present on the surface of polymers with a low entanglement density following a single sliding pass. No debris were present on the surface of polymers with a high entanglement density following a single sliding pass. A relationship between entanglement density and debris production was confirmed by studying different crosslink densities of polystyrene. Localised plastic deformation occurring at the exposed surface region was proposed to explain the formation of debris. The friction of different crosslink densities of polystyrene was shown to be indifferent when measured by a glass indenter and by a silicon nitride scanning probe microscope tip. Micro-Raman spectroscopy was employed to detect molecular orientation in thin polymer films resulting from friction processes.