An exploration of the relationship of chemical and physical parameters in the micromechanical characterisation of the apparent interfacial strength in glass fibre epoxy systems

This paper focuses on the cure shrinkage and the thermomechanical properties of an amine cured epoxy resin system and its adhesion to glass fibre. The fibre-matrix interfacial shear strength (IFSS) was characterized using the microbond test over a range of test temperatures and a range of amine:epoxy ratios. The apparent IFSS in this glass-epoxy system was shown to be strongly dependent on the testing temperature and the matrix stoichiometry. High levels of cure shrinkage were measured in the IFSS microdroplets which resulted in internal stresses causing significant levels of droplet deformation. The results presented here can be interpreted as providing further support for the hypothesis that a significant fraction of the interfacial stress transfer capability in epoxy composites can be attributed to a combination of residual radial compressive stress and static friction at the fibre-matrix interface.