EFFECT OF ELECTROLYTIC OXIDATION ON THE SURFACE-CHEMISTRY OF TYPE-A CARBON-FIBERS .1. X-RAY PHOTOELECTRON-SPECTROSCOPY

The surface chemistry of type A carbon fibres was investigated by using X-ray photoelectron spectroscopy. Oxidation in an aqueous ammonium bicarbonate electrolyte was carried out to model the industrial surface treatment. The changes in the surface chemistry were monitored, and the concentrations of surface oxygen and nitrogen were found to increase with the degree of fibre treatment. Water and hydrocarbon adsorption onto the fibre surface upon exposure to ambient conditions has also been monitored, which helps to clarify the inconsistencies between oxygen concentration determined from the O1s data and C1s curve fitting data in the literature. The nitrogen present in the surface after oxidation was shown to be in a different chemical state to that on the untreated fibre. It is postulated that the protonated amine that exists on the untreated fibre would be capable of reacting with the epoxy resin functionalities, whereas the nitrogen containing functional group or groups present after surface treatment would not.