Surface characterization and properties of keratin fibers treated with low-temperature plasmas

Abstract

The relation between shrink-resistance properties and surface changes (wettability, atomic chemical composition and topographical or morphological) induced by low-temperature plasmas (LTPs) has been studied in depth. For this purpose, plasma treatments with air, nitrogen and water vapor were carried out. Different surface techniques, such as contact angle measurement on single fiber, XPS analysis, SEM observations and Herbig sac formation, have been used. Also, the free radical formation was studied by EPR spectroscopy. It has been demonstrated that the plasma gas can be contaminated with water coming from the wool or the walls of reactor chamber. The fatty acid monolayer present on the outermost part of the fiber surface is progressively removed with increasing treatment time, but at short treatment time the oxidation of hydrocarbon chains prevails over its removal. The free radical formation depends on the treatment time and the plasma gas used. The shrinkage phenomenon of wool fabrics is found to be related also to the outermost surface chemical composition of the fiber.