Influence of oxyfluorination on transport mechanical properties of pan-based carbon fibers

In this work, the effect of oxyfluorination on surface characteristics of carbon fibers was investigated in terms of fracture toughness and crack resistance properties of the epoxy matrix composites. The surface properties of the carbon fibers were determined by the acid-base values, X-ray photoelectron spectroscopy (XPS), and FT-IR measurements. And their fracture toughness of the composites was studied in critical stress intensity factor (K_IC) and critical energy release rate mode II (G_IIC). As the experimental XPS results showed, O_1S/C_1S ratio was increased by oxyfluorination, due to the oxygen-containing functional groups and the format in the C-F_x bonds on carbon fiber surfaces. It was found that the fracture toughness and crack resistance of the composites were improved by the oxyfluorination, which could probably be attributed to the increase of the degree of adhesion at the interfaces between the carbon fibers and epoxy resin matrix in the present composite system.