Water management of human hair

Abstract

Citation: IFSCC Magazine, 10 (2007) (4) 317–320Temperature dependent isotherms for the water ab‐ and desorption of human hair were determined (25–65°C) together with the related diffusion coefficients and hysteresis effects. Special care was taken to standardize the physical history of the samples. With increasing temperature, isotherms, while preserving their shape, shift to lower regains while the hysteresis effect decreases. This is in accordance with expectations derived from the Rosenbaum‐model for water sorption. The differential heat of water sorption changes from dry to wet hair between 1020 and 50 J/g H2O. Diffusion coefficients are of the order of 10‐9 cm2/s. The coefficients increase with temperature and show a pronounced maximum in the range of medium regains. The temperature dependence follows the Arrhenius equation and exhibits activation energies that change from dry to wet hair between 55 and 30 kJ/mol. The sorption performance of strongly bleached hair, with and without an additional treatment with cetyltrimethylammonium bromide, was investigated. No significant effects either of the cosmetic treatment or of the ingredient were found. It is concluded that human hair exhibits a rather robust static and dynamic water sorption performance that, against initial expectations, is not readily changed by cosmetic processes and ingredients.Keywords: cosmetic treatments, diffusion coefficients, human hair, hysteresis, water sorptionPaper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands