Water vapor sorption and desorption behavior of some keratins

Summary Sorption and desorption isotherms of water vapor in a number of keratin substrates including excised human stratum corneum, guinea pig and neonatal rat corneum and human hair have been obtained and the data compared to the information available on wool. An attempt was made to analyze the data according to the BET and D'Arcy-Watt equations, Flory-Huggins polymer solution theory and Zimm's clustering function. The results suggest strong binding between the sorbate and keratins in the low relative vapor pressure range, reflecting a sorption process on primary reactive sites (Langmuir) which proceeds up to 0.2-0.3 relative vapor pressure. More confirmation is obtained from isosteric heat of sorption measurements. Extensive clustering and multilayer formation occur in the higher relative vapor pressure range.With 10 figures