Test methodA simple test method for measuring water vapor resistance of porous polymeric materials

A simple test method is proposed for measuring water vapor resistance of fabrics. A piece of cotton fabric connected to a container filled with distilled water through a plastic tube was used on a hot plate to generate a saturated water vapor condition on one side of the sample. The temperature of the cotton fabric (approximation of human skin covered with sweat) was measured by a thermocouple. The water vapor resistance of the sample was determined based on the water vapor pressure gradient across the sample and the heat flux. Five types of textile fabric laminated to PU/TPU membranes, plus one type of conventional fabric, were tested by using this simple apparatus as well as the sweating guarded hot plate instrument. The results showed that good agreement was observed between these two test methods. In addition, the surface temperature of the cotton 'skin' varied with different fabrics. This is in accordance with the actual intended situation, i.e., the skin temperature of the body is related to the ability of clothing materials to transfer water vapor. Therefore, this simple test apparatus better simulates real-life conditions than the sweating guarded hot plate instrument.