Thermal insulation property of graphene/polymer coated textile based multi-layer fabric heating element with aramid fabric

This study investigated the thermal insulation properties based on electrical heating test of graphene-based multi-layer fabric heating elements to confirm the possibility of application for fabric heating element for protective clothing. Four layers were designed as layers of outer, filler, electrical heating textile, and lining. The outer fabrics used two different densities of aramid woven fabrics (LD_ARW and HD_ARW), an aramid knit (AR_KT), and nonwoven (AR_NW). Fabricated graphene/polymer coated electrical heating textile (GR) exhibits a surface temperature of about 85 °C, a current of 0.12 A, and a power of 3 W when 30 V is applied. As composed with 4-layer, the surface temperature of LD_ARW and HD_ARW used as the outer for sample indicated less than 50 °C, due to their excellent heat resistance property; whereas, when AR_KT and AR_NW were used, the temperature was about 50 °C. This is because their fine fibers form high porosity that can entrap air. As a result of the thermal insulation properties, the temperature difference of each layer was in the order ΔT((GR-N3)) < ΔT((GR-Lining)) < ΔT((GR-Outer)). In particular, when AR_NW was used as the outer fabric, ΔT((GR-Outer)) was decreased by about 10 °C, compared with that of the other outer fabric. By the effect of relative humidity under dry 25% RH and comfortable 55% RH, the temperature difference was decreased under 55% RH; thus, the thermal insulation property was improved under comfortable humidity condition. Therefore, the best thermal insulation performance was exhibited when AR_NW was used as outer under 55% RH, and it is expected to expand its application to fabric heating element for protective clothing.