Effects of plasma oxidation on the surface and interfacial properties of carbon fibres/polycarbonate composites

Two types of carbon fibres, ultra-high modulus (pitch-based) and high stren gth (PAN-based), were submitted to an oxygen plasma treatment. Single filam ent tests were performed to evaluate the effects of the treatment on the me chanical properties of the fibres, Weibull analysis of the tensile data rev ealed no substantial changes in the tensile strength after fibre oxidation. Fragmentation tests performed on carbon fibre/polycarbonate composites sho wed that the plasma treatment increases significantly the interfacial shear strength. This demonstrates the ability of the cool plasma oxidation to en hance the adhesion of carbon fibres to polycarbonate. The possible influenc es of the structural and chemical properties of the carbon surfaces upon th e final response of the interface were investigated using inverse gas chrom atography (IGC) at infinite dilution. The increase of surface functional gr oups induced by the plasma treatment seems to be the main reason for the im provement of the interfacial adhesion. (C) 2001 Elsevier Science Ltd. All r ights reserved.