Water Transport and Wrinkle Recovery of Wool

Abstract

A "ratchet" mechanism is discussed for the formation and recovery of wrinkles in wool fabric. During the wrinkling stage, in which local temperature and humidity are raised, stress relaxation rates are increased by the lowering of the glass transition temperature by plasticization with water, by the ambient increase in temperature, and by additional heating caused by a positive heat of sorption. During recovery, the temperature and relative humidity decrease, giving a greatly reduced relaxation rate that delays wrinkle recovery. On the assumption that wrinkle behavior can be improved by reducing the rate of water transport, measurements were made of the water desorption rate from a fabric taken from 86% to 65% RH. Fabrics were treated with phenyl isocyanate, urea, acetic anhydride, esterification with methanol, potas sium dichromate, and mercuric acetate. Although a part of the altered wrinkle behavior may be due to changes in equilibrium water content, the data suggest that slowing the desorption rate is a primary factor in improving wrinkle recovery.