Moisture Transfer in Textile Systems, Part II

Abstract

While the moisture permeability index and insulation value define the heat transfer characteristics of fabric systems under equilibrium conditions, such conditions do not always occur. Moisture may accttmulate in clothing during periods of activity due to unevaporated sweat or sweat which has evaporated from the skin and recondensed in cooler layers of clothing, or to moisture which is absorbed by the textile fibers. Upon cessation of activity and sweating, this moisture accumulated in the clothing will evap orate and produce undesired cooling or "after-exercise chill." A special thermostated hot plate is described which is used to measure rates of heat transfer through fabrics before, during, and after periods of simulated sweating. Typical curves are given for absorptive and nonabsorptive systems measured under conditions in which no excess moisture secretion or recondensation takes place. An interpretation of these curves is suggested. It is shown that with an absorptive textile the after-exercise chill is large and persists for about two hours but with a nonabsorptive type it is negligible.