Wettability of Wool Fibers

The critical surface tension of wool fibers was measured using the sink-float technique with various classes of test liquids. Nonpolar organic liquids and aqueous surfactants gave similar values of γ, but much lower values were obtained with butanol/water mixtures. Adsorption of butanol on the surface of the fibers is thought to be responsible for the low values of γ in the latter case. Removal of lipid material from the surface of fibers by extraction increases γ from 30 mN/m to 37 mN/m, similar to that obtained for horn keratin or polypeptide material. Exposure of fibers to a corona discharge in air at atmospheric pressure also increases γ.