Test EquipmentA new test method for determining water vapor transport properties of polymer membranes

The water vapor transport properties of polymer membranes are critical in applications of waterproof breathable clothing materials. Several test methods are available for measuring the permeability of polymer membrane or laminates but they are either time-consuming or require large amounts of sample. A new test apparatus was devised for determining the water vapor permeability of polymer materials. A cylinder covered with waterproof but vapor-permeable PTFE film was used to form a water vapor source. Dry nitrogen gas was utilized to carry the penetrated vapor away. This new apparatus offers a short test duration (5 min) and small sample size. The subsequent measurements showed that the water vapor diffusion resistance of one layer of microporous PTFE membrane was 5.2 s/m. Additionally, the water vapor transport behavior of the PTFE membrane does not depend upon the water content in the polymer.