Thermal and water vapor resistance of the elastic and conventional cotton fabrics

The research focuses on the influence of elastane (Spandex) incorporation in the weft direction of cotton fabrics, and the structural properties (fabric density, type of weave) on the thermal and water vapor resistance level. For that purpose, woven fabrics, in plain and twill weave with two different densities (17 and 20 yarns/cm) in the weft direction, were made from 100% cotton (conventional) and from a mixture cotton/elastane in the ratio 93.8%/6.2% (elastic fabric) intended for men’s shirts for the summer season. Thermal and water vapor resistance were determined with two novel methods, which were compared with the well-known Permetest method. The thermal resistance was calculated according to the thermal conductivity method which was established by the faculty research laboratory and with the Permetest, while the water vapor resistance was measured with the water cup method (developed by Professor D. Jaksic) and with the Permetest. The research results indicate that cotton fabrics in twill weave with elastane in the weft direction have higher thermal and water vapor resistance compared to conventional cotton fabrics. The reason lies in the higher yarn density of fabrics with elastane in the weft direction in twill weave (from 24 to 29–31 yarns/cm in the warp direction) compared to the plain weave (from 24 to 28 yarns/cm in the warp direction).