Yielding and Fracture Toughness of Glass Microballoon-Filled Epoxy Composites

The yielding and fracture behaviour of epoxy/glass microballoon composites has been studied as a function of filler content, temperature and strain rate. No increase in elastic modulus, yield stress and fracture toughness was observed. The compressive yield stress of the composites showed strain rate dependence with more than one rate-activated yielding process. The fracture toughness parameters G_c and K_c were found to be temperature insensitive. The variations in the measured mechanical quantities are discussed in terms of the observed morphology and thermal behaviour of the epoxy composites.