Influence of thermal and surface treatments on surface properties of pitch-based carbon fibers studied by inverse gas chromatography

Abstract

Surface properties of pitch-based carbon fibers submitted to various final heat treatment temperatures (HTT) and various surface oxidation degrees have been studied by means of inverse gas chromatography (IGC) at both infinite dilution and finite concentration. The results show that the surface of the carbon fibers is energetically heterogeneous with the predominance of graphitic basal plane sites. The elevation of the HTT reduces both the dispersive component of surface energy ( γ S D ), which is related to the high energy sites such as surface defects and highly polarisable heteroatoms, and the surface acidity, which is governed by the surface oxygenated functional groups. The anodic oxidation introduces acidic sites while not changing very much the γ 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 organic matrix.