XPS study of carbon fiber surfaces treated by thermal oxidation in a gas mixture of O 2/(O 2+N 2)

Abstract

X-ray photoelectron spectroscopy (XPS) has been used to investigate the surface characteristics of two carbon fibers and determine the role of surface treatment in improving the properties of a carbon fiber composite. Carbon and oxygen were the major elements observed on the surface of the carbon fiber samples. Small amounts of lightly oxidized nitrogen amounting to about 3 at.% were detected on the surface of thermally oxidized carbon fiber in a gas mixture of O 2/(N 2+O 2). Graphitic carbon was the major carbon functional component on the surface of carbon fiber 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 fibers with and without surface treatment was in the carbonyl group (CO) content. Thermal oxidation processing in a gas mixture of O 2/(N 2+O 2) can be employed to increase the carbonyl functional group which is the main contributor in improving the interlaminar shear strengths of carbon fiber composite materials.