Preparation and thermal properties of microencapsulated stearyl alcohol with silicon dioxide shell as thermal energy storage materials

Abstract

Microencapsulation of stearyl alcohol (SAL) with silica shell using sol-gel method has been attempted to obtain microencapsulated phase change materials (MPCM). Tetraethoxysilane (TEOS) was used as silica precursor to form silica shell. In order to inveatigate thermal properties of the MPCM, some tests were carried out. The results of Fourier transformation infrared spectroscope (FT–IR) indicated that the combination of the SAL with silica by sol-gel method is a physical action. X–ray diffractometer (XRD) was used to confirm PCM maintains stable crystal structure. Scanning electronic microscope (SEM) was employed to determine the MPCM has relatively stable physical structure. Thermal properties of MPCM were measured by Differential scanning calorimeter (DSC), where melting temperature and latent heat of MPCM1 (made from 10 g SAL, 10 g TEOS) is 55.89 °C and 229.73 J/g, respectively. Liquid–solid phase change has latent heat of 112.05 J/g at 56.74 °C while solid-solid phase change has latent heat of 72.01 J/g at 49.75 °C. Thermogravimetric analyzer (TGA) analysis confirms that MPCM has good thermal stability. After 100 thermal cycles of the MPCM1, there was no change in phase transition temperature and latent heat, which confirms that the MPCM has good reliability. The thermal conductivity of MPCM1 was measured to be 0.1508 W/m·K over melting point of MPCM1 and 0.1412 W/m·K at room temperature. Therefore, MPCM1 is found to be a promising candidate for thermal energy storage applications.