Thermal properties of combat uniforms treated with microencapsulated octadecane and change in clothing microclimate via thermal manikin

Abstract

This study examined how the heat storage property and the heat release property of three different PCM (Phase Change Material) treatment concentrations of combat uniform fabrics affected microclimate inside clothing after the octadecane-treated fabrics were made into garments. Three combat uniforms were constructed with fabrics treated by three different octadecane concentrations (0, 8, and 16%) at the same curing temperature of 113.6 °C. The thermal properties of the octadecane-treated fabrics were acquired by using DSC (Differential Scanning Calorimeter) analysis. Also, water vapor and air permeability were measured before the thermal comfort of the octadecane-treated combat uniforms was evaluated. And then, a thermal manikin was used to measure skin temperature, skin humidity, and microclimate temperature, while the chamber was set at various environmental temperatures (0, 0–35, 35, and 35–0 °C). And, to analyze the differences among skin temperature, skin humidity, and microclimate temperature of the garments according to the three different octadecane concentrations, ANOVA and a post hoc test were conducted. As a result, heat of fusion and heat of crystallization (ΔHf and ΔHc) were observed to increase as the octadecane concentration increased. The 8% octadecane-treated fabrics had 3.56 J/g of ΔHf, 3.80 J/g of ΔHc, and the 16% octadecane-treated fabrics had 7.46 J/g of ΔHf, 7.44 J/g of ΔHc. Also, the more octadecane was added, the less water vapor and air permeability had the fabrics because many open spaces were covered due to the microcapsules after octadecane treatment. It might influence on clothing microclimate. However, the 8% octadecane-treated garment (G1) exhibited less differential skin temperature and humidity and clothing microclimate temperature than the 16% octadecane-treated garment (G2) even though the octadecane concentration was lower. It means that the 8% octadecane-treated garment exhibited better thermal performance than the 16% octadecane-treated garment. This is because the higher octadecane concentration caused the fabric to become stiffer, thereby causing the still air layer to decrease the thermal insulation efficiency and the octadecane treatment was not affected. It differed from the result of the thermal properties (ΔHf and ΔHc) of the octadecane-treated fabrics. The reason for this result is that when the thermal manikin wore the octadecane-treated garments, various factors had effects on thermal properties such as environmental aspects, physiological aspects, and clothing aspects.