DRYING PROCESSES OF FABRICS

Abstract

Drying properties of cotton, nylon and wool fabrics were studied.The fabrics were cut into 10cm square and wetted out by soaking in distilled water more than 2hr. The weight of the wet sample placed in a box at 20°C and 65% R. H. was read off at regular intervals until it reached a nearly equilibrium value. The sample was then dried at 105±5°C to determine the net weight and the moisture regain.Drying rates during the initial constant rate period, Rc (T), were almost equal. For such different fabrics, the activation energy of drying during this period was about 11.5kcal/mol which was similar to the heat of evaporation of liquid water.The critical moisture contents (c. m. c) of the fabrics could be identified with the regains obtained by the extrapolation of the curves of the desorption isotherms to 100% R. H.For three different cotton fabrics, the drying rates during the falling rate period (Rf) had very good relation to the fiber content, not to fabric thickness.In several studies, Rf has been assumed to be directly proportional to the moisture content, but the characteristic curves observed for the cotton, nylon and wool fabrics were convex upward.This paper proposes the relation between Rf and moisture regain (X). Rf is affected only by the regain and temperature in the fabrics and not by fabric structure or thickness.