A review of interphase formation and design in fibre-reinforced composites.

This paper reviews the surface treatment and sizing of reinforcing fibres used for manufacturing composites. Carbon fibre surface treatment and coating is discussed primarily to identify the mechanism of interphase formation. In this case, adsorption of sizing polymers is shown to be an integral part of the interaction with matrix polymers. ToFSIMS imaging was used to identify the locus of failure and confirm the nature of the interphase. In the case of glass fibres the hydrolysis of the silane coupling agent is shown to be critical. The surface chemistry of the glass controls the degree of polymerisation of the polysiloxane and hence the interaction with the matrix polymer whether it be thermoplastic or thermoset. For completeness a brief review of the surface treatments of advanced polymer fibres is also included. The role of the interphase in the micromechanics of the failure of fibre composites is also modelled and discussed in an attempt to provide design guidelines for composite manufacture.