Rubber toughening of plastics

Abstract

Measurements of tensile yield stress, compressive yield stress and kinetics of tensile creep have been carried out fora series of HIPS polymers containing “salami” structure rubber particles of median diameter 1.6 µm which account for 35, 22.5, 17.5, 10.5 and 3.5% of the total volume, respectively. Deformation is due to multiple crazing in tension and shear yielding in compression; the dependence of yield stress upon rubber particle volume fraction is similar but not identical in the two cases. Eyring plots of log (creep rate) against applied stress are used to determine stress concentration factors for each member of the series, and the results are discussed in terms of the Goodierequations for an isolated spherical inclusion, and the Ishai-Cohen model for average stress concentrations.