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 filter content, temperature and strain ra te. No increase in elastic modulus, yield stress and fracture toughness was observed. The compressive yield stress of the composites showed strain rat e dependence with more than one rate-activated yielding process. The fractu re toughness parameters G(c) and K-c were found to be temperature insensiti ve. The variations in the measured mechanical quantities are discussed in t erms of the observed morphology and thermal behaviour of the epoxy composit es.