Determination of surface heterogeneity by contact angle measurements on glassfibres coated with different sizings

This study has been achieved on industrial products (glassfibres coated with different sizings). Contact angle measurements and contact angle hysteresis were obtained with three liquids (glycerol, tricresylphosphate and mineral oil). Fibres are perfectly wetted with tricresylphosphate and mineral oil contrary to glycerol. For this last liquid a large distribution of contact angle and contact angle hysteresis were observed. Three parameters were used to analyse the results: places where filaments were extracted in the roving (inside or at the periphery), roughness and heterogeneity of the filaments surfaces (chemical heterogeneity). Statistical measurements of contact angles have shown heterogeneity in the roving. Atomic force microscopy (AFM) measurements have shown that roughness has only a weak contribution to the large distribution observed on the wetting results with glycerol. This large distribution and the contact angle hysteresis were due to the chemical heterogeneity of the fibres' surfaces. (C) 1999 Kluwer Academic Publishers.