Effect of Dy2O3 on thermal properties of adipic acid (AA) as phase-change materials

Abstract

In this work, the effect of rare-earth dysprosium oxide (Dy2O3) on the thermal stability properties of adipic acid (AA) matrix was investigated in detail. The AA/Dy2O3 composites were prepared by melting and mixing method. The microstructure, phase composition and thermal properties of AA/Dy2O3 composites were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and differential scanning calorimeter, respectively. It was found that there was a gradual change in melting temperature and latent heat of fusion after 1000th thermal cycles and the thermal stability of AA can be enhanced by incorporation of Dy2O3. The obtained AA doped with 3.0 mass% dysprosium oxide exhibited a small decline of only 3.2% in the melting latent heat after 1000th cycling tests compared with the decline of 13.7% for pure AA. In addition, the phase transition temperature was 142.1 °C with 227.9 J g−1 in the latent heat of fusion by adding 3.0 mass% dysprosium oxide after 1000th melting/freezing cycles. There was no chemical reaction between AA and Dy2O3 phase during the melting/freezing process, and the AA showed no obvious change in the structures after 1000th melting/freezing cycles. The Dy2O3 particles exhibited a homogenous dispersion in the AA matrix even after 1000th melting/freezing cycles.