THE EFFECT OF SURFACE-TREATMENT ON THE INTERFACIAL PROPERTIES IN CARBON FIBRE EPOXY MATRIX COMPOSITES/

Carbon fibres with different degrees of surface oxidation, as well as epoxy-sized fibres, were used to prepare epoxy composites in order to compare the effects of the fibres surface chemistry on the interfacial properties. X-ray photoelectron spectroscopy, water vapour adsorption measurements and contact angle examination were applied to characteri ze the carbon fibre surfaces. A correlation was found between the cont ent of primary adsorption sites on the fibre surface and interlaminar shear strength (ILSS) of the composites. Higher values of ILSS obtaine d for the oxidized fibres containing composites are proposed to be due to the higher concentration of carboxylic groups created on the oxidi zed fibres surface and to the creation of chemical bonds at the fibre/ epoxy matrix interface. Enthalpy of cure, reaction peak temperature an d glass transition temperature of the composites were determined by di fferential scanning calorimetry.