Development and characterization of modified sepiolite-based composite phase change materials for building thermal management

To enhance the purity and hydrophobicity of sepiolite, sepiolite (ST) was modified by different concentrations of hydrochloric acid (HCl) and octyltrimethoxysilane (OS), resulting in modified sepiolite (ST m ). A stable composite phase change material (LA-PA/ST m ) was prepared by vacuum adsorption method using a certain amount of ST m mixed with a binary eutectic phase change material of lauric acid and palmitic acid (LA-PA). The results showed that ST m0.5 , modified by 0.5 mol·L −1 hydrochloric acid and OS, exhibited the strongest adsorption capacity. When the mass fraction of ST m0.5 in LA-PA/ST was 66 %, LA-PA was evenly distributed in the pores of ST m0.5 without leakage in the molten state. Compared with pure LA-PA, the thermal conductivity of LA-PA/ST m0.5 was 1.12 W·m −1 ·k −1 , an improvement of 386.21 %. At 100 °C, the mass of LA-PA/ST m0.5 remained unchanged, indicating good thermal stability. The experiment on heat storage and release under lighting proves that the temperature control performance improves as the content of LA-PA/STm0.5 in the cement paste increases, indicating a broad development prospect in the field of building thermal management.