The catalytic effect of platinum on the oxidation of carbon fibres

Ex-PAN based carbon fibres (5C) were oxidized at 500, 550 and 600 degree C in dry air while being contained in both silica and platinum specimen holders. The weight loss measurements taken as a function of time revealed that those fibres oxidized in platinum exhibited a much higher oxidation rate than those exposed in silica. Additionally, those fibres oxidized in platinum underwent unusual changes in fibre morphology. 'Spheres' formed along the longitudinal axis of many fibres, and in one instance, a-fibre underwent bifurcation, with a sphere forming on each remaining fibril. Likewise, severe surface pitting occurred. It is believed that these changes in microstructure combined with the increased oxidation rate are a result of a catalysed oxidation reaction(s) caused by the presence of platinum, or perhaps by a co-catalytic reaction between platinum and impurities found on the surface of the fibres.