XPS study of carbon ®ber surfaces treated by thermal oxidation in a gas mixture of O2/(O2 ‡ N2)

X-ray photoelectron spectroscopy (XPS) has been used to investigate the surface characteristics of two carbon ®bers and determine the role of surface treatment in improving the properties of a carbon ®ber composite. Carbon and oxygen were the major elements observed on the surface of the carbon ®ber samples. Small amounts of lightly oxidized nitrogen amounting to about 3 at.% were detected on the surface of thermally oxidized carbon ®ber in a gas mixture of O2/(N2 ‡ O2). Graphitic carbon was the major carbon functional component on the surface of carbon ®ber samples but other functional forms of carbon were also present such as C±O, C=O, and O±C=O. The biggest differences in the surface chemistry between the carbon ®bers with and without surface treatment was in the carbonyl group (C=O) content. Thermal oxidation processing in a gas mixture of O2/(N2 ‡ O2) can be employed to increase the carbonyl functional group which is the main contributor in improving the interlaminar shear strengths of carbon ®ber composite materials. # 2001 Elsevier Science B.V. All rights reserved.