Analysis of the Influencing Factors of the Thermal Performance of Fabrics

Thermal conductivity K is a parameter used to characterize the thermal conductivity of a material, and it is one of the basic physical properties of a material. The smaller the value, the worse the thermal conductivity of the material and the better the thermal insulation. The heat transfer systems of various textile materials are shown in the table below. Table 1 Thermal conductivity of textile materials (measured at room temperature 20 ℃) ​​Material K (W/m·°C) Material K (W/m·℃) Cotton 0.071～0.073 Polyester 0.084 Wool 0.052～0.055 Acrylic 0.051 Silk 0.050～0.055 Polypropylene 0.221～0.302 Viscose 0.055～0.071 Spandex 0.042 Acetate 0.050 Air 0.026 Nylon 0.244～0.337 Water 0.697 Air has the smallest thermal conductivity and is the best thermal insulator. Under normal circumstances, the thermal conductivity of textile materials that we do not have is actually the thermal conductivity of the mixture of fibers, air and moisture, and the porosity of the fabric is generally 70% to 80%, so the thermal conductivity of textile materials is very large. The extent depends on the state and amount of air trapped in the fiber layer. Under the premise of no air flow, the more air is retained in the fiber layer, the better the thermal insulation of the fiber layer. Therefore, the fabric is soft, thick, and contains a lot of air, and the heat preservation is good. The brushed fleece fabric has better heat preservation than the general fabric, also because a certain thickness of air layer is maintained between the piles. However, once the air in the fabric flows, the thermal insulation of the fabric is greatly reduced. The thermal conductivity of water is relatively large, about 10 times that of general textile materials, and approximately 30 times that of air. Therefore, water has a great influence on the warmth retention of the fabric. Generally speaking, after the fabric is wetted, the thermal conductivity of the fabric will increase and the warmth retention will decrease. More about Thermal Protection Performance Testers: http://www.standard-groups.com/TextileGarment/