INFLUENCE OF THERMAL AND SURFACE TREATMENTS ON SURFACE-PROPERTIES OF PITCH-BASED CARBON-FIBERS STUDIED BY INVERSE GAS-CHROMATOGRAPHY

Surface properties of pitch-based carbon fibers submitted to various f inal heat treatment temperatures (HTT) and various surface oxidation d egrees have been studied by means of inverse gas chromatography (IGC) at both infinite dilution and finite concentration. The results show t hat the surface of the carbon fibers is energetically heterogeneous wi th the predominance of graphitic basal plane sites. The elevation of t he HTT reduces both the dispersive component of surface energy (gamma( S)D), which is related to the high energy sites such as surface defect s and highly polarisable heteroatoms, and the surface acidity, which i s governed by the surface oxygenated functional groups. The anodic oxi dation introduces acidic sites while not changing very much the gamma( S)D. It is found that the high energy sites and surface acidity play a dominant role in reinforcing ability of the carbon fibers with organi c matrix.