Studies on mechanical interfacial properties of oxy-fluorinated carbon fibers-reinforced composites

In this work, the effect of oxy-fluorination on physicochemical properties of polyacrylonitrile (PAN)-based carbon fibers has been investigated. The chemical composition of the oxy-fluorinated carbon fibers is determined by X-ray photoelectron spectroscopy (XPS) measurement. Mechanical interfacial properties, such as interlaminar shear strength (ILSS), fracture toughness (KIC), work of fracture (Wf) and fracture energy (GIC) of the composites are also studied in terms of oxy-fluorination conditions. From the surface analysis, it is found that oxy-fluorination led to an introducing of the fluorine and oxygen functional groups on carbon fiber surfaces, which are more efficient and reactive to undergo an interfacial reaction to matrix materials. Moreover, the formation of CFx physical bonding of the carbon fibers with fluorine increases the surface polarity of the fibers, resulting in increased ILSS, KIC, Wf and GIC of the composites, due to the improvement of interfacial adhesion between fibers and matrix resins.