Anodic surface oxidation mechanisms of PAN-based and pitch-based carbon fibres

In order to clarify the differences in the anodic surface oxidation mechani sms of PAN-based and pitch-based carbon fibres, the fibres were oxidized in an electrolyte and characterized using the coulostatic method, X-ray photo electron spectroscopy, laser Raman spectroscopy, and X-ray diffraction. The interfacial bonding strength to an epoxy resin was evaluated based on the interlaminar shear strength (ILSS). The results showed a good correlation b etween the differential double layer capacities, which were measured with t he coulostatic method, and the ILSS values of PAN-based high tensile streng th carbon fibres (PAN-HTCFs), PAN-based high modulus carbon fibres (PAN-HMC Fs), and pitch-based high modulus carbon fibres (pitch-HMCFs). Their morpho logies for the anodic oxidation were as follows: PAN-HTCFs are anodized hom ogeneously; pitch-HMCFs are selectively oxidized and promote crevice etchin g; and PAN-HMCFs resist crevice etching due to the many defects in the hexa gonal network. (C) 1999 Kluwer Academic Publishers.