XPS Analysis of Carbon Fiber Surfaces—Anodized and Interfacial Effects in Fiber–Epoxy Composites

Abstract

High strength carbon fibers were electrochemically treated in an aqueous ammonium carbonate solution, with increasing electric current density, using an original continuous treatment process. The electrochemical treatment induced a modification of the surface properties, i.e., surface functional groups as observed by XPS. As a result, the O1s/C1s and the N1s/C1s 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. However, no significant change in the surface functional activity characters was observed for strong treatments. Hence, a moderate treatment (30 A m−2) was sufficient to obtain optimum (O1s + N1s)/C1s ratios in this system. This treatment is possibly suitable for carbon fibers to be incorporated in a polar organic matrix, resulting in increasing the interlaminar shear strength (ILSS) of the resulting composites.