Surface characteristics of electrochemically modified carbon fibers in phosphoric acid solution: Effect of surface treatment on interfacial mechanical behaviors of composites

Electrochemical surface treatment of PAN-based carbon fibers in acidic elec trolyte has been studied in increasing the surface acidic functional groups on fibers for the improvement of composite interfacial adhesion. With a vi ewpoint of acid-base interaction chemistry, low current densities are need for the changing of morphological and mechanical properties, This study rev eals that anodic treatment under weakly oxidizing conditions in phosphoric acid electrolyte for 10 sec leads to surface modification of the fibers, pr eferentially prismatic planes. According to acid value, XPS and interfacial mechanical property measurements, it is revealed that the oxygen functiona l groups on fibers are largely dominated in composite mechanical behavior, whereas the nitrogen functional groups are not affected in the system studi ed. Also, a good correlation between surface acidic functionality and mecha nical properties is established, and it is found that 0.4 A.m(-2) current d ensity is the optimum conditions for this system.