THE BONDING MECHANISM OF ARAMID FIBERS TO EPOXY MATRICES .2. AN EXPERIMENTAL INVESTIGATION

In this study attempts are made to develop a basic understanding of the interfacial interactions resulting from the combination of aramid fibres with epoxy matrices in composite materials. The interfacial interactions examined are mechanical stresses due to fibre-matrix thermal strains and Poisson's ratio mismatch, covalent chemical bonding, fibre-matrix wetting, and effects of physicochemical weak boundary layers. Both aramid and carbon fibres have been examined to assess the interfacial interactions by comparing the behaviour of these two fibres in the same matrices. The results indicate that the adhesion of aramid fibres to epoxy matrices lack both the mechanical and the chemical interactions present at the carbon-epoxy interface. Aramid fibres exhibit an interfacial shear strength much lower than the expected theoretical value. Direct observation of the aramid-epoxy interface by transmission electron microscopy shows fibrillar separations within the fibre surface, which may be the limiting factor in achieving greater interfacial adhesion. © 1990 Chapman and Hall Ltd.