Effect of Boron Nitride on the Heat Transfer and Heat Storage of Poly(ethylene glycol)/Expanded Vermiculite Composite Phase-Change Materials

In this work, the expanded vermiculite/poly(ethylene glycol)–boron nitride (E/PB-X) shape-stabilized composite phase-change materials with the encapsulation capacity of ∼66.16 wt % were prepared by a typical vacuum impregnation method to overcome liquid leakage during phase transition and poor thermal conductivity during heat transfer of poly(ethylene glycol). It was found that the boron nitride showed a great influence on the heat transfer and heat storage of E/PB-X. The thermal conductivity of E/PB-X was 0.45–0.49 W/(m·K), indicating that the heat transfer of E/PB-X was significantly enhanced by the dispersed boron nitride fillers, which was mainly attributed to the reduction of interfacial thermal resistance and the formation of rapid thermally conductive channels. However, the latent heat (∼55.76 J/g) of E/PB-X decreased with the increase in the boron nitride content, revealing that the heat storage behavior of E/PB-X was strongly affected by the confinement of surface interactions of boron nitride and expanded vermiculite, which was consistent with the crystallization behavior determined by X-ray diffractometer (XRD) results. Moreover, the spectroscopy (FT-IR) and thermogravimetric analyzer (TGA) results confirmed that E/PB-X exhibited excellent chemical compatibility and thermal stability, respectively, which were conducive to practical heat storage applications.