A smart textile fabric with two-way action

The aim of the paper was to develop a prototype of smart textile material with shape memory elements that give variable thermal insulation dependent on the emission-absorption of heat. Shape memory elements were made in the form of spirals of two-way action from nitinol (NiTi) one-way wire. Two groups of samples were made: active and non-active. The active spirals expand at temperatures lower than the characteristic inner state transition temperature and contract as the temperature becomes higher than the transient temperature, which was about 45℃. The non-active spirals do not change dimensions under the influence of heat supply. The material of the layered structure was prepared. The first layer consisted of cotton woven fabric and the second layer featured a system of NiTi spiral elements, while the final layer was made of a thin Teflon foil. The behavior of samples during absorption-emission of heat was studied. Temperature measurements were conducted using an infrared camera; samples were placed on a heater to ensure contact between the Teflon layer and the base, and the temperature was recorded at the sample surface (woven fabric) as a function of the heating time for both active and non-active samples. A theoretical model that makes it possible to determine the time variable thermal parameters of the smart textile material was developed. Good agreement between the experimental and theoretical results was received. The temperature on the surface of the active sample was approximately 10℃ higher at the end of heating than the temperature of the non-active sample after the same heating pattern.