26—water-Vapour Adsorption Isotherms of Wool

Experiments are described in which wool–water-vapour adsorption isotherms were determined gravimetrically in the temperature range 20–100°C by using a quartz helical spring mounted in an evacuable apparatus. Major factors affecting the measured water content of the wool samples are identified as the previous history of the sample, the amount by which the vapour pressure is changed, and the time allowed for equilibrium to be established; the influence of these factors becomes more marked at higher temperatures. Careful control of these variables in the study reported in this paper enabled reproducible isotherms to be obtained by employing a set of specified conditions. Complete adsorption isotherms were determined over a wider range of temperatures than was previously possible. Comparative isotherms are presented for a series of wools from different sources and for other forms of keratin subjected to similar pre-treatment and measurement procedures.