Comprehensive analysis of the thermal properties of capric-myristic, lauric-myristic and palmitic-stearic acids and their shape-stabilization in an inorganic support

Abstract

Complete thermal characterization was performed to the binary eutectics capric-myristic (CA:MA), lauric-myristic (LA:MA) and palmitic-stearic (PA:SA). The obtained thermophysical properties included theoretical calculus along with experimental measurements as phase change temperatures, latent heats, specific heat capacities and degradation temperatures, through modulated differential scanning calorimetry (MDSC) and thermogravimetry analysis (TGA). Likewise, vacuum-assisted method was successfully employed to produce novel shape-stabilized phase change materials (SS-PCMs), with a porous clay mineral as a support, using different impregnation percentages (25%, 35% and 40%) of CA:MA, LA:MA and PA:SA. Thermal properties were obtained in the same manner as for the binary eutectic mixtures, besides, scanning electron microscope (SEM) was used to study the SS-PCMs morphologies and leakage test performed. From the MDSC measurements, empirical equations of specific heat capacity as a function of temperature were proposed for the binary eutectics and SS-PCMs. The results of this work revealed that the optimal percentage of CA:MA, LA:MA and PA:SA was 35%, in terms of low leakage (<2%), latent heats around 45 kJ kg−1 and average heat capacities of 1.4 J g−1°C−1. As the new composites presented a wide range of phase change temperatures then SS-CAMA (23°C), SS-LAMA (36°C) and SS-PASA (55°C) can be used for diverse applications as in construction, food industry and domestic hot water tanks.