Kinetic Study of the Wool-Water System

Abstract

The kinetics of the uptake of water vapor by wool is dependent on the initial con centration of water and the size of the concentration increment. For small concentration increments, absorption may occur in two stages, the second stage much slower than the first. For any set of conditions, the previous treatment of the wool with respect to water vapor affects the observed kinetics and the equilibrium concentration of water in the fibers. It is shown that first stage absorption to a quasi-equitibrium obeys Fick's laws of diffusion with a concentration-dependent diffusion coefficient. The apparent activation energy of diffusion varies with concentration. Second-stage absorption is accompanied by irreversible configurational changes within the fibers. Detailed data of two-stage behavior is presented in order to test the relevance to the wool-water system of the hypothesis previously proposed that in polymer-penetrant system seçond- stage absorption occurs as a result of stress relaxation within the sorbent.