Preparation and Characterization of a Binary Form-Stable Composite Phase-Change Material Based on n-Decanol and n-Octanoic Acid.

Phase-change energy storage materials have the potential to improve the durability of hydraulic concrete; however, phase-change materials suitable for dam engineering within the 0-5 °C phase-transition range remain limited. In this study, a binary phase-change material was prepared by melt blending n-decanol (DA) and n-octanoic acid (CA). Expanded vermiculite (EV), with a layered porous structure, was selected as the form-stabilizing support matrix. A thermally stable DA-CA/EV composite phase-change material was then prepared by melt impregnation and adsorption, and its thermal properties, shape-stabilization performance, and thermal reliability were systematically characterized. The results indicate that the optimal binary composition is 35 wt.% DA and 65 wt.% CA, with a solidification phase-transition temperature of 2.5 °C and a latent heat of 163 kJ/kg. Moreover, the use of 100-mesh EV as the supporting matrix effectively prevents leakage. The optimal thermal conductivity is achieved when approximately 50 wt.% PCM is adsorbed while a high bulk density is maintained. Owing to its favorable thermal performance and structural stability, the prepared PCM shows promise for application in hydraulic concrete.