Surface functionalisation of carbon nano-fibres in fluidised bed plasma

Vapour grown carbon fibres were treated in a plasma to enhance the surface energy and thus to improve the bonding to the polymer matrix. To achieve uniform treatment, the fibres were fluidised either by mechanical vibration or in a gas stream (fluidised bed). The plasma treatment using CO2-Ar and O2-Ar as process gases leads to an increase in the polar component of the surface energy. The dispersive component (representing roughness) does not change. The surface energy, obtained from contact angle measurement, is determined by the concentration of oxygen containing functional groups on the surface. The concentration of these groups was measured by XPS.