Abstract:

Objective In developing textiles, wearable devices, aerospace and other fields, the core element of intelligent temperature regulation function is based on the use of phase change temperature regulating fibers. As the basic unit of intelligent temperature regulating textiles, phase change fibers mainly combine phase change materials with matrix materials through various spinning technologies. With the increasingly serious energy crisis and environmental protection problems, the development of thermal energy storage materials with environmental protection characteristics is very important for the sustainable development of energy. At present, there are limited studies on phase change fibers (membranes) based on biodegradable materials and phase change materials. Therefore, it is of great significance to develop biodegradable phase change fiber materials (membranes) with high latent heat.

Method Polyactic Acid (PLA) nanofiber membrane has good biodegradability, and as a phase change material, disodium hydrogen phosphate dodecahydrate (DHPD) is widely used in the field of thermal energy storage. Through adding phase change materials to PLA nanofibers, the fiber membrane can achieve temperature regulation function. In this study, DHPD was used as a phase change functional material, and PLA was used as a carrier for encapsulating phase change materials. The biodegradable fiber membrane with temperature regulating function was prepared by electrospinning technology. The morphology structure, thermal energy storage performance and thermal regulation performance of the temperature-regulated fiber membrane were analyzed. In addition, the thermal cycle performance, wettability and water absorption performance of the temperature-regulated fiber membrane were evaluated.

Results When the mass fraction of PLA was 8% and the mass ratio of PLA to DHPD was 40∶4, the nanofiber membrane with an average fiber diameter of 342 nm was successfully prepared. The results showed that the fiber surface of the thermoregulated fiber membrane was smooth and continuous, and the morphology of the fiber membrane was also good. The heat storage performance of the temperature-regulating fiber membrane was studied and analyzed, and it was found that after adding DHPD, the thermal properties of the thermoregulated fiber membrane changed significantly. With the increase of DHPD mass, the melting enthalpy and crystallization enthalpy of the thermoregulated fiber membrane were significantly improved. When the mass ratio of PLA to DHPD is 40∶4, the melting temperature of the thermoregulated fiber membrane was 42 ℃, and the melting enthalpy was 1.96 J/g. The temperature-regulated fiber membrane showed an obvious exothermic peak at 31-33 ℃, and 31.85 ℃ was the crystallization temperature, when the crystallization enthalpy was 1.49 J/g. Thermal imaging technology was used to test and analyze the thermal regulation performance of the thermoregulated fiber membrane on human simulated skin. It was clearly observed that the final temperature difference of the thermoregulated fiber membrane with a mass ratio of PLA to DHPD of 40∶0 and a mass ratio of PLA to DHPD of 40∶4 was 0.3 ℃ during the 80 s period. The surface temperature of the thermoregulated fiber membrane with a mass ratio of PLA to DHPD of 40∶4 was increased by only 3.7 ℃. After 50 heating and cooling cycles, the shrinkage of the thermo-regulated fiber membrane decreased with the increase of DHPD mass ratio, indicating that the addition of DHPD had an effect on the thermal stability of the thermo-regulated fiber membrane. Finally, the wettability and water absorption properties of the thermoregulated fiber membrane were analyzed. The results showed that the addition of DHPD had an effect on the hydrophilicity and water absorption of the thermoregulated fiber membrane. When the mass ratio of PLA to DHPD was 40∶4, the water contact angle of the thermoregulated fiber membrane reached 110°, and the water absorption rate reached 689%.

Conclusion In summary, a biodegradable fiber membrane with temperature regulation function was successfully prepared by electrospinning technology in this research with a simple route. When the mass ratio of PLA to DHPD is 40∶4, the heat storage performance and thermal regulation performance of the thermo-regulated fiber membrane are both good. In addition to the unique flexibility of the fiber membrane, this temperature-regulated fiber membrane also has good heat storage performance, thermal regulation, reusability and water absorption. The temperature-regulated fiber membrane prepared by this method also provides a new strategy for the development of environmentally compatible thermal energy storage textiles.

Key words: polylactic acid, temperature controlled nanofiber membrane, smart textile, phase change fiber, electrospinning, disodium hydrogen phosphate dodecahydrate