The fibre/matrix interphase and the adhesion mechanism of surface-treated TwaronR aramid fibre

In order to optimize the adhesion to an epoxy matrix, TwaronR aramid fibre requires a pretreatment with an epoxy/hardener solution. The chemical composition of the pretreated fibre surface was analysed using X-ray photoelectron spectroscopy and static imaging secondary ion mass spectrometry. To this end model epoxy monomers were synthesized and use was made of a fluorine-labelled hardener. The effects of processing steps such as ageing of the pretreatment solution and curing of the epoxy/hardener at the fibre surface have been systematically analysed. Our results show that polar interactions between the aramid and epoxy molecules play a dominant role in the interfacial adhesion mechanism. There is evidence to suggest that the epoxy layer introduced onto the surface of the TwaronR filaments is inhomogeneous as a result of the processing conditions.