Anomalous Diffusion in a Water Vapour Permeable Waterproof Coating

摘要

An earlier study had been carried out to evaluate several methods of measuring the water-vapour resistance of coated, waterproof, but water-vapour permeable fabrics. The results, which are reported elsewhere were inconsistent. It was found that the resistance values of individual fabrics and the ranking of the fabric within the series of fabrics varied from method to method. When the results and methods were examined, it became apparent that the fabrics with hydrophilic coatings had water-vapour resistance values which were humidity-dependent. The water-vapour resistance of such fabrics was high when the fabric was tested using a method in which the fabric was in relatively dry air. Conversely, the water-vapour resistance was low when the fabric was tested by a method in which the fabric was adjacent to a wet surface. This paper reports the experiment carried out to examine the effect of relative humidity on the water-vapour resistance of a water-vapour permeable coated fabric. Only one experiment was carried out because, upon its completion, it was discovered that other workers had independently formulated and tested the same hypothesis with similar results.