Effects of exfoliated graphite on the thermal properties of erythritol-based composites used as phase-change materials

Erythritol-based composites were prepared with various concentrations of exfoliated graphite (EG) via a simple impregnation method. The effects of varying the EG content on the thermal conductivity, latent heat, melting point, and thermal cycling stability of the erythritol-based composites were studied. The results showed that the thermal conductivities of the composites increased as the EG content increased, but the initial latent heats decreased. The thermal conductivity of the composite containing 4 wt.% of EG was significantly enhanced compared to that of pure erythritol (2.06 and 0.31 W/mK, respectively), while the melting point of the composite decreased from 120.10 °C to 116.32 °C. In addition, the results of the thermal cycling tests (for which 5 cycles were performed) showed that the degree of energy loss decreased as the EG content increased because of the worm-like shape and porosity of EG. The results of this study indicate that EG can improve the outstanding thermal conductivity and thermal cycling stability of erythritol-based composites that are used as phase-change materials (PCMs).