Selective oxidation of carbon to enhance both tensile strength and interfacial adhesion of carbon fiber

Among the various techniques utilized for surface modification of carbon fiber, the most practical one for commercial production is anodization due to its controllable oxidation level in a continuous process. During the traditional process, the adhesion between the fiber and epoxy resin can be improved, but at the expense of reducing tensile strength. Here, we present a novel anodic oxidation method, i.e., the carbon atoms on the ridges are selectively oxidized and those in the grooves remain intact. In this way, the longitudinal grooves on the fiber surface become shallow and the tensile strength of fiber shows an obvious increase by comparison with the carbon fiber oxidized via traditional oxidation method. More importantly, due to the high density of oxygen-containing groups on the ridges, the fiber shows great wetting properties and strong adhesion to epoxy resin.