Effect of Temperature on Moisture Permeability of Cotton and Poly(ethylene terephthalate)Fabrics.

Abstract

The moisture permeability of cotton and poly (ethylene terephthalate) (PET) fabrics in the isothermal system were investigated in the artificial climate room. The experiments were carried out in conformity of the JIS L 1099 A-2. The temperature of 20°C and 35°C, the relative humidity 20-80% and the windless condition were selected for the experimental conditions. The air permeability of fabric was measured at 20°C and the relative humidity 20-80%.The effect of temperature on the moisture permeability of fabrics could be replaced by the effect of the difference in moisture-vapour concentration (ΔC) on both sides of fabrics. As Δ C increased from the origin (ΔC=0), the moisture permeability of fabrics increased remarkably. The increase of the moisture permeability of fabrics by the ΔC increase at 35°C was almost on the extension of the line of that at 20°C. It can therefore be presumed that the increase of the moisture permeability by the temperature increase is caused by the ΔC increase for the temperature increase. Compared with the effect of ΔC to the moisture permeability of fabrics, the effects of materials and of the variation of the diffusion coefficient of moisture in air by temperature change were small.The total resistance (R) of system to the passage of the moisture was small at low temperature and at small ΔC.The air permeability of PET fabrics was larger than the cotton fabric, and the air permeability of fabrics changed slightly with the change of the environmental humidity.