Synthesis and properties of microencapsulated octadecane with silica shell as shape-stabilized thermal energy storage materials

•Shape-stabilized octadecane and silica microcapsules were prepared by using sol-gel method.•Chemical structure, crystalloid phase and microstructure of the MPCMs were investigated.•Thermal properties and reliability of the MPCMs were determined and analyzed.•The silica shell can improve thermal stability of the CPCMs and prevent the octadecane from leakage.

In this work, shape-stabilized octadecane and silica microcapsules were prepared by using sol-gel method. In the microcapsules, the octadecane was used as phase change material (PCM) for thermal energy storage, and the silica prepared from methyl triethoxysilane (MTES) acted as shell material to prevent the octadecane from leakage. The thermal properties of the microcapsules were measured by differential scanning calorimeter (DSC). The microstructure and particle size of the microcapsules were surveyed by scanning electronic microscope (SEM). Fourier transformation infrared spectroscope (FT-IR) and X-ray diffractometer (XRD) were used to investigate the chemical structure, crystalloid phase of the microcapsules. The DSC results showed that the satisfactory microencapsulated phase change material (MPCM) sample melts at 28.32 °C with a latent heat of 227.66 kJ/kg and solidifies at 26.22 °C with a latent heat of 226.26 kJ/kg. The thermal reliability of the microcapsules was analyzed by a thermogravimetric analyzer (TGA). The results indicated that the MPCMs have good thermal stability, which could be used as shape-stabilized phase change materials for thermal energy storage.

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