Analytical investigation of plasma-treated carbon fibres

As-grown and heat-treated vapour grown carbon fibres (VGCF) in the as-prepared state, washed in HCl/H2O, and treated in O-2 plasma for different periods have been investigated by means of XPS and scanning electron microscopy (SEM). The surface energy of the carbon fibres before and after plasma treatment was determined from the wetting contact angle. Washing introduced hydroxyl, carbonyl and carboxyl groups onto the fibre surfaces and oxygen plasma treatment increases the total atomic concentration of oxygen up to 17%. This is in good agreement with the value of the polar component of the surface energy. Plasma treatment also enhanced the fibre surface porosity (by etching).