Effect of Test Methods on Apparent Moisture Vapour Transmission of P/V and P/C Fabrics

The moisture vapour permeability properties of a series of almost similar polyesterviscose (P/V) and polyester-cotton (P/C) blended fabrics are investigated. The water vapour transport rate greatly differs depending on the principle of the test methods, even when other parameters are nearly identical, such as air permeability, areal density, porosity and thickness. The water absorption characteristics of fibre seem to be the most important in determining the overall water vapour transport rate. Substitution of polyester for viscose and cotton in P/V and P/C blended fabrics respectively, reduces the water transport rate of the fabrics in a long term method. It is found that the P/C blended fabrics show greater water vapour transport than the corresponding P/V fabrics when a long term test method is used; however, the P/V fabrics show relatively higher water vapour permeability than the P/C fabrics when short duration tests are carried out by using the Permetest and moisture vapour transmission rate (MVTR) ...