Effect of Temperature on Water Vapor Transport Through Polymer Membrane Laminates

摘要

This report determines the extent to which the water vapor transport properties of nine different polymer membranes and membrane/textile laminates are affected by temperature. A particular test method, the Dynamic Moisture Permeation Cell (DMPC), is ideally suited for this type of study, due to its complete control over the humidity and gas flow rate on the two sides of the test sample, and the ability to control the temperature of the test system. This allows temperature-dependent effects to be separated from concentration-dependent effects on mass transfer phenomena. The DMPC permits the experimenter to explore the temperature dependence of the diffusion behavior at different points on the vapor sorption isotherm of the hydrophilic polymer component of a polymer film or membrane laminate. Temperature effects are shown to be much less important than concentration-dependent effects in a hydrophilic polymer layer. Observed changes in water vapor flux at different temperatures are primarily due to the relationship between temperature and the saturation vapor pressure of water, and not to intrinsic changes in polymer permeability.