SURFACE-PROPERTIES OF CARBON-FIBERS DETERMINED BY INVERSE GAS-CHROMATOGRAPHY - ROLE OF PRETREATMENT

Untreated, oxidized, and sized carbon fibers have been analyzed by inverse gas chromatography at infinite dilution, as a function of pretreatment temperature (105, 150, and 200-degrees-C) in situ in a chromatography column under a helium atmosphere. The dispersive component of surface energy, gamma-s(D), and the acid-base character were determined. For untreated and oxidized fibers, the surface properties are strongly dependent upon thermal pretreatment. The dispersive component of surface energy and the acidity increase with pretreatment temperature, and weak basicity also appears. This behavior can be explained by the desorption of gases retained on the active surface sites of the fiber. The relative stability of the sized fiber stresses the protective role of polymer sizing.