Heat storage/release characteristics and mechanical properties of combat uniform fabrics treated with microcapsules containing octadecane as phase change materials

Combat uniform fabric was treated with octadecane-containing microcapsules to impart thermostatic function in this study. Size and morphology of microcapsules, and quantity of octadecane in the microcapsules were investigated. Heat release and storage properties with respect to a variety of treatment conditions was also investigated. Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), thermogravimetric analysis-differential thermal analysis (TGA-DTA), and differential scanning calorimeter (DSC) were used to measure the properties of treated fabrics. Tensile properties, including tensile strength and elongation at break, and toughness, were measured by universal tensile testing machine in a conditioned environment (20±1 °C, 50±5 % RH). Microcapsules were round-shaped and sized between 4.22 and 4.92 µm with thermal stability under 110 °C of treatment temperature. Heat of fusion (ΔH_f) and heat of crystallization (ΔH_c) of the specimens increased along with the increase of microcapsule concentration. However, they decreased as the treatment temperature increased, at 12 % and 18 % of microcapsule concentrations. In case of specimens treated by 24 % of microcapsule concentration, ΔH_f and ΔH_c increased when specimens were cured at higher temperatures. Tensile strength of specimens decreased as treatment temperature increased. Elongation at break of all specimens decreased after treatment, but no specific tendency was observed. Toughness of all specimens exhibited a tendency of increase as concentration of microcapsules increased. Among the 9 treated specimens, specimen treated with 24 % of microcapsules and 110 °C of curing temperature had the best heat storage/release and mechanical properties for combat uniform.