Abstract:

Objective As consumption levels rise, people's demands for the thermal comfort of clothing have also gradually increased. Phase change textiles, as a type of product with two-way temperature regulation functions, have emerged in the public eye. In order to develop phase change fibers with suitable phase change temperatures and good spinnability, phase change fibers and phase change fabrics were prepared by combining hollow polyester fibers with binary fatty acid mixtures, and their phase change temperature regulation properties were tested.
Method A hollow polyester fiber was selected as the fiber substrate, and the mixture of binary fatty acids of lauric acid (LA) and capric (CA) acid was used as the phase change substance. The low integration effect of fatty acids was adopted to adjust the temperature range of the phase change substance, and the phase change polyester fiber was prepared by combining the hollow polyester fiber substrate with the binary fatty acid phase change substance by vacuum impregnation method. The factors affecting the enthalpy conversion rate of the phase change fiber prepared by vacuum impregnation method were theoretically derived.
Results Through vacuum impregnation, phase change material of CA-LA binary fatty acids was filled into the cavities of hollow polyester fibers. The resulting phase change polyester fibers are a type of fiber with a shell-core structure as observed under electron microscopy, where hollow polyester serves as the wall material and the CA-LA binary fatty acid mixture serves as the core material. No significant damage occurs to the fiber surface before and after treatment. Additionally, the phase change polyester fibers and hollow polyester fibers were processed through carding, netting, twisting, knitting, and other processes to obtain ribbed knitted fabrics. The temperature control range of the prepared CA-LA phase change polyester fibers could be effectively adjusted by modifying the molar ratio of the two components in the CA-LA binary fatty acid mixture. When the molar ratio of the two components in the CA-LA binary fatty acid mixture is CA/LA=21∶79, the temperature range of the prepared phase change polyester fibers aligns with the comfortable temperature requirements of the human body. When two pieces of fabric were placed from a 20 ℃ environment into a 40 ℃ environment, the curve of the treated fabric remains below that of the untreated fabric at the same contact time, with a smaller slope. After 150 s of contact, the temperature of the treated fabric is 30.7 ℃, while the temperature of the untreated fabric is 33.8 ℃, and the surface temperature of the former is 3.1 ℃ lower than that of the latter. Even after multiple thermal cycles, the treated fabric showed that it could still regulate temperature effectively, indicating possible applications in sportswear, bedding, and other similar fields.
Conclusion In summary, when the molar ratio of CA/LA is 21∶79, the phase change temperature range of the obtained CA-LA/PET phase change fibers aligns with the thermal comfort requirements of the human body. The phase change polyester fiber is produced by combining fatty acid phase change materials with hollow polyester fibers using the vacuum impregnation method, resulting in a smooth and undamaged surface, and the knitted fabric made from it exhibits stable temperature regulation performance. A theoretical model for the combination of hollow fibers and phase change materials was established, and theoretical analysis revealed that the main factors affecting the enthalpy conversion rate of phase change fibers via the vacuum impregnation method include the hollowness of the hollow fibers, the density of the hollow fibers, the density of the phase change materials, and the melting enthalpy of the phase change materials, with correlation formulas derived between these factors.

Key words: phase change fiber, hollow polyester, vacuum impregnation, binary fatty acid, enthalpy conversion rate, functional textiles