Characterization of a porous mineral as a promising support for shape-stabilized phase change materials

Several characterization techniques were used to identify and quantify the mineralogical phases of a Colombian mineral that could be used as a suitable porous support for shape-stabilized phase change materials (SS-PCMs). The mineral was calcined in a laboratory box furnace at 600 degrees C, 900 degrees C and 1100 degrees C. The phase evolution and microstructure were investigated by X-ray fluorescence (XRF), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Through the Rietveld refinement method the phases were quantified. The results showed that the mineral was composed of 19.75% kaolinite, 11.88% quartz, 10.75% illite, and 40.00% diatomite. Preliminary SS-PCMs were produced through vacuum assisted impregnation. Lauric-myristic acid binary eutectic was prepared and then incorporated at 25 wt.% (SS-LAMA25), 35 wt.% (SS-LAMA35), and 40 wt.% (SS-LAMA40) into the raw mineral. The leakage obtained for the composites was between 0.1% and 4.9%. Differential scanning calorimetry (DSC) showed a latent heat of fusion of 29.63 kJ/kg, 51.57 kJ/kg and 56.59 kJ/kg, and phase change temperatures of 35.39 degrees C, 36.35 degrees C and 36.17 degrees C, for the SS-LAMA25, SS-LAMA35 and SS-LAMA40, respectively.