Preparation and Thermal Properties of Myristic Acid/Hydrophobic Fumed Silica/Hexagonal Boron Nitride Composite Phase Change Material

Abstract

To address the issues of leakage and poor thermal conductivity in organic solid-liquid phase change materials, this study prepared a shape-stabilized composite phase change material using myristic acid (MA) as the phase change energy storage matrix, hydrophobic fumed silica (FS) as the porous carrier, and hexagonal boron nitride (BN) as the thermally conductive filler via a solvent-assisted impregnation method. The composite material was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The results indicate that the composite with an MA mass fraction of 65 % exhibits both satisfactory shape stability and a relatively high latent heat of phase change. The sample with 2 % BN addition demonstrates the best overall performance, with melting and solidification temperatures of 52.47 °C and 51.89 °C, and melting and solidification latent heats of 115.6 J/g and 110.8 J/g, respectively. The thermal conductivity is increased by 83.6% compared to the composite without BN, and the addition of BN also showed a preliminary effect in reducing the supercooling degree. The composite system shows application potential for low‑to‑medium temperature solar thermal storage, providing a theoretical basis and technical reference for the development of efficient, low‑cost, and scalable phase change energy storage materials.