Particle toughening of polymers by plastic void growth

An analysis is given for the toughening of particle filled polymers assuming that plastic void growth around debonded, or cavitated particles is the dominant energy absorbing mechanism. The controlling parameter is the debonding (or cavitation) surface energy which triggers the growth of a plastic void around the particle which in turn enhances the toughness. Literature data are examined for particles ranging from 0.01 to 25 μm in radius in thermoset resins and it is found that the surface work for very small particles is the surface work of adhesion while for larger sizes it is some fraction of the matrix toughness. This larger debonding energy is found to be proportional to the particle radius. Large toughness increases are predicted, and observed, in the nano-range, i.e. 0.01 μm which are shown to require good particle dispersion and high matrix ductility. More modest increases are predicted at the micron scale but these are more robust.