Thermal resistance of polyurethane-coated knitted fabrics before and after weathering

Polyurethane-coated knitted fabrics are of interest because they exhibit several positive properties, they are more stretchable, elastic and comfortable than coated woven fabrics and yet they are little studied. Information of weather durability, as well as thermal properties, is essential to ensure thermal protection for textile materials intended for outdoor use. In the presented research, a series of coated knitted fabrics for protective clothing were developed and exposed to weathering in summer and winter seasons. After three months of outdoor exposure, thermal resistance of all the tested materials decreased by 13% after the summer season and 25% after the winter season. A very good correlation of knitted fabric mass per unit area and thermal resistance of knitted fabric, coated fabric and aged coated fabric occurred. The studied materials experienced a partial degradation of the polyurethane layer, which is not related to the deterioration of the knitted substrate. The presented investigation of thermal resistance of coated fabrics and their dependence on the knitted substrate, as well as the influence of environmental conditions, allows the improvement of coated fabrics with the aim of better thermal protection.