A novel mild method for surface treatment of carbon fibres in epoxy-matrix composites

The interface quality between the reinforcement and the host matrix plays a key role in the mechanical performance of Carbon Fibre/Epoxy Resin (CFRP) composites. In most cases, an adequately strong interfacial bond is induced chemically either by the oxidation of the carbon fibre (CF) surface and/or by means of mechanical interlocking (friction). Here, a mild chemical process involving CF's functionalization via an epoxidation reaction at room temperature (RT) is being proposed. By immersing the CF in an organic solution (chloroperoxybenzoic acid in dichloromethane), the outer surface is functionalized with oxygen moieties, such as epoxy rings, at optimized grafting densities. The room-temperature method described here is more advantageous that other oxidative treatments since it is cost-effective, environmentally friendly and does not damage the fibre surface. Furthermore, as detected by Laser Raman microscopy a considerable 2.3-fold increase of the maximum interfacial shear stress was observed for the treated CF/Epoxy systems as compared to the pristine-untreated-samples.