Electric heating garment can improve the thermal comfort for people living and working in cold environment. Compared with passive heating materials, electrical heating shows dominant advantages on reusability, controlled temperature, safety and so on. This review article systematically introduced the material preparation, electric-thermal properties, advantages and disadvantages of the existing flexible heating elements, and elaborated the research and application progress of smart garments in detail, providing reference for the research of flexible heating elements and smart garments. And the existing challenges and the possible future perspectives were also discussed.

It is necessary to develop a novel low-temperature protective material that ensures the flexibility and warmth of operation in a short time under the low-temperature environment (−30 to −80 C). Hence, a novel multilayer low-temperature protection composite (MPC) was prepared based on phase change microcapsules (microPCMs). MicroPCMs containing n-octadecane with melamine-urea-formaldehyde shell were successfully synthesized through in situ polymerization. Then the microPCMs were finished on the basic fabric's surface (biocomponent spunbond-spunlace nonwoven material) by foam coating and the silicone rubber was covered on the outermost surface. On the basis of scanning electron microscope (SEM) micrographs, microPCMs had a relatively spherical shape and a smooth surface, in which the average particle size was about 42.77 μm. The cross section morphology showed that the MPC was consisted of three layers structure including the base fabric, the microPCMs layer, and the silicone rubber layer. At −50 C, the low-temperature resistance time of the MPC was 727 s and the power consumption for maintaining a certain temperature for 10 and 20 min of the MPC were 350.86 and 1392.66 J, respectively. Compared with the basic fabric, which has the same thickness as the MPC, the low-temperature resistance time of the MPC was prolonged about 5 min and the power consumption of the MPC for 10 min decreased by 55%, and for 20 minutes decreased by 33%, respectively. The MPC could guarantee the low-temperature protection effect in short time. It could be applied as the potential materials in the area of low-temperature protection.

The excellent mechanical property and light weight of protective materials are vital for practical application in body armor. In this study, O2-plasma-modified multi-walled carbon nanotubes (M-MWNTs) were introduced into shear-thickening fluid (STF)-impregnated Kevlar woven fabrics to increase the quasi-static stab resistance and decrease the composite weight. The rheological test showed that the addition of 0.06 wt. % M-MWNT caused a marked increase in the peak viscosity from 1563 to 3417 pa·s and a decrease in the critical shear rate from 14.68 s−1 to 2.53 s−1. The storage modulus (G′) and loss modulus (G″) showed a higher degree of abrupt increase with the increase of shear stress. The yarn pull-out test showed that the yarn friction of M-MWNT/STF/Kevlar fabrics was far superior to the original fabrics. Importantly, under similar areal density, the M-MWNT/STF/Kevlar fabrics could resist 1261.4 N quasi-static stab force and absorb 41.3 J energy, which were much higher than neat Kevlar fabrics. The results of this research indicated that quasi-static stab resistance was improved by M-MWNTs, which was attributed to the excellent shear-thickening effect and the high yarn friction. Therefore, M-MWNT/STF/Kevlar fabrics have a broad prospect in the fields of body protection.

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