Analysis of the wool- water sorption isotherm: An old problem revisited

Analysis of the wool- water sorption isotherm: An old problem revisited Franz-Josef Wortmann1 , Alexandra Hullmann2, Crisan Popescu3, 1 University of Manchester, School of Materials, Manchester, United Kingdom2 Kao Professional Salon Services GmbH, Darmstadt, Germany3 DWI at RWTH Aachen University, Aachen, GermanyThe fact that wool and other animal fibres of textile relevance can absorb up to 35% water before being ???wet??? is one of their fundamental properties and has major consequences for their use in fibre and textile processing. Water sorption in keratins follows with relative humidity a rather simple sigmoid isotherm that is characteristic for a large and very diverse variety of materials. Various models to analyse the wool/water sorption isotherms and to use them for water content prediction have been developed and investigated in the past. These generally have been shown, however, to have various types of deficiencies for the consistent description of the isotherms. Against this background, the Rosenbaum model and other equivalent approaches appear to have superior physical plausibility. During this first stage of our investigations we determined whether this type of model provides a simple, stable and physically consistent algorithm for the description of the water sorption isotherms of wool, including their temperature dependence. This would enable to readily and reliably predict the water content of wool for any given humidity/temperature combination. Furthermore, the Rosenbaum-model contains features which may enable to further develop our understanding of the phenomenon of water sorption hysteresis.