XPS analysis of carbon fiber surfaces - anodized and interfacial effects in fiber-epoxy composites

High strength carbon fibers were electrochemically treated in an aqueous am monium carbonate solution, with increasing electric current density, using an original continuous treatment process. The electrochemical treatment ind uced a modification of the surface properties, i.e., surface functional gro ups as observed by XPS. As a result, the O-1s/C-1s and the N-1s/C-1s ratios of the fiber surfaces increased with the increase of current intensity of the electrochemical treatment in the interval of about 30-50 A m(-2). Howev er, no significant change in the surface functional activity characters was observed for strong treatments. Hence, a moderate treatment (30 A m(-2)) w as sufficient to obtain optimum (O-1s + N-1s)/C-1s ratios in this system. T his treatment is possibly suitable for carbon fibers to be incorporated in a polar organic matrix, resulting in increasing the interlaminar shear stre ngth (ILSS) of the resulting composites. (C) 1999 Academic Press.