Synthesis and properties of microencapsulated stearic acid/silica composites with graphene oxide for improving thermal conductivity as novel solar thermal storage materials

Abstract

Phase change materials (PCM) have stable operation temperature and large storage capacity. However, PCM have problems of leakage and low thermal conductivity. For improving performances of PCM, stearic acid (SA) was encapsulated in silica shell by sol-gel method to form microencapsulated phase change materials (MPCM), and graphene oxide (GO) was attached to surface of silica by a self-assembly process to form GO@MPCM, so as to further improve performances of MPCM. The morphology of MPCM was observed through a scanning electronic microscope (SEM). The chemical structure and crystal phase of MPCM were measured by Fourier transformation infrared spectroscope (FT–IR) and X–ray diffractometer (XRD). Raman spectrometer was used to further verify that GO was attached to the MPCM. Thermogravimetric analyzer (TGA) analysis confirmed that MPCM have good thermal stability. Thermal properties of MPCM were measured by Differential scanning calorimeter (DSC), where melting temperature and latent heat of MPCM2 is 67.78 °C and 179.29 J/g. The melting temperature of GO@MPCM is similar to that of MPCM2, and the melting latent heat of GO1 @MPCM and GO2@MPCM is 146.72 J/g and 134.42 J/g, respectively. Besides, thermal conductivity of MPCM with GO is higher than that of pure SA.