ABSTRACT

Abstract-Keratin fibers are hydrophobic in nature due to the presence of an outermost monolayer of fatty acids, which are covalently bonded to proteins of the fiber cuticle surface membrane via ester or thioester linkages, with the methylene or ethylene groups oriented towards the outermost fiber surface. This characteristic exerts considerable influence on the shrinkage of wool fabrics submitted to aqueous washing process, on the adhesion to other materials, and on the dye diffusion into the fiber bulk. It is known that the hydrogen peroxide at alkaline pH, or low-temperature plasma (L TP) treatments provide hydrophilic properties to the fiber surface and, consequently, the shrinkage is reduced and the adhesion and dye diffusion are enhanced. This study focuses on the relationship between surface composition and wetting behavior of keratin fibers. For this purpose, wetting force measurements on single fibers according to the Wilhelmy procedure and XPS analysis were carried out on chemically-modified or plasma-treated keratin fibers. Whereas the scale direction of untreated keratin fibers does not exert any influence on the advancing adhesion tension values, it exerts a considerable influence on the receding ones. This behavior was found to be related to the different chemical compositions existing between the dorsal and the frontal parts of the fiber scales. The oxygen relative atomic concentration determined by XPS analysis is well correlated to advancing water contact angle values and it can be used to predict wetting behavior of keratin fibers.