The resin/hardener ratio as a processing parameter for modifying the mechanical behaviour of epoxy-matrix glass microsphere composites

An investigation has been carried out on the variation of the mechanical properties of a composite consisting of glass microspheres in an epoxy resin, as a function of the processing of the matrix. The resin/hardener ratio was used as the processing parameter and composites were fabricated with stoichiometric and non-stoichiometric matrix formulations. The experimental results show that the mechanical properties were significantly altered and that the hardener-rich formulation had the best deformation capacity. In order to model the experimental results obtained for the elastic modulus of the composites, an efficiency factor, related to the adhesion characteristics of each resin-formulation/glass-microsphere pair, was derived and applied to one of the existent theoretical models. (C) 1998 Elsevier Science Ltd. All rights reserved.