X‐ray photoelectron spectroscopic studies of carbon fibre surfaces. III—Industrially treated fibres and the effect of heat and exposure to oxygen

Abstract

AbstractCarbon fibres, surface treated by an industrial process, were analysed by x‐ray photoelectron spectroscopy (XPS). The results allow the surface chemistry to be compared with that achieved by controlled laboratory methods. It is found that industrial treatment has less control over individual fibre surface treatment than in the laboratory treated fibres, and that the reproducibity of treatment varies with the treatment method. As the level of treatment is increased the spectra show an increase in the C/O and C/N surface functional groups. In contrast to the laboratory treated fibres there is no identifiable difference in the types or proportions of C/O groups with the amount of surface treatment, and the overall changes in the spectra are much less. The type and proportion of surface groups between treated and untreated fibres are different. C=O type groups appear to dominate in the treated fibre samples over O—O— type groups. Mass spectroscopic analysis associated with heat treatment can be very usefully combined with XPS analysis in the same apparatus as an aid to the understanding of complex industrially treated samples. Thus the effect of surface treatment can be effectively reversed by heat treatment to very high temperatures, with the regeneration of a fibre surface which resembles that of the untreated fibre surface. Exposure of the heated fibre after cooling to gaseous oxygen causes little change in the surface chemistry.