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

This study has been achieved on industrial products (glassfibres coated wit h different sizings). Contact angle measurements and contact angle hysteres is were obtained with three liquids (glycerol, tricresylphosphate and miner al oil). Fibres are perfectly wetted with tricresylphosphate and mineral oi l contrary to glycerol. For this last liquid a large distribution of contac t angle and contact angle hysteresis were observed. Three parameters were u sed to analyse the results: places where filaments were extracted in the ro ving (inside or at the periphery), roughness and heterogeneity of the filam ents surfaces (chemical heterogeneity). Statistical measurements of contact angles have shown heterogeneity in the roving. Atomic force microscopy (AF M) measurements have shown that roughness has only a weak contribution to t he large distribution observed on the wetting results with glycerol. This l arge distribution and the contact angle hysteresis were due to the chemical heterogeneity of the fibres' surfaces. (C) 1999 Kluwer Academic Publishers .