Structure and thermal properties of stearic acid/silica composites as form-stable phase change materials

In this study, stearic acid/silica phase change composites were prepared by the sol-gel method using stearic acid as phase change materials (PCMs). The effects of mass fraction of stearic acid were comprehensively investigated. The structures and thermal properties of the obtained composites were characterized by various methods, including scanning electron microscopy (SEM), differential scanning calorimetry (DSC), leakage tests, and thermogravimetry analysis (TG). The results indicated that composite containing 76% stearic acid had the best thermal properties and low mass leakage, making 76% stearic acid as the maximum content that silica matrix could protect in the composites. The latter was further confirmed by morphological analyses of the silica matrix. Silica matrix exhibited spherical particle clusters, following big-small-big-small size pattern as stearic acid rose. The composite with 76% stearic acid was at the key point of change in particle size. These findings look promising for future to prepare silica-based phase change composites with good thermal properties easily. [GRAPHICS] The composite containing 76% stearic acid showed good thermal properties. Silica particle size changed with stearic acid content in composites. The composite with 76% stearic acid was at the key point of change in particle size.