Synthesis and properties of microencapsulated paraffin composites with SiO2 shell as thermal energy storage materials

Microencapsulated paraffin composites with SiO2 shell as thermal energy storage materials were prepared using sol–gel methods. In the microencapsulated composites, paraffin was used as the core material that is a phase change material (PCM), and SiO2 acted as the shell material that is fire resistant. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine chemical structure, crystalloid phase and microstructure of microencapsulated paraffin composites with SiO2 shell, respectively. The thermal properties were investigated by a differential scanning calorimeter (DSC). The thermal stability was determined by a thermogravimetric analyzer (TGA). The SEM results showed that the paraffin was well encapsulated in the shell of SiO2. The DSC results indicated that the microencapsulated paraffin composites solidify at 58.27 °C with a latent heat of 107.05 kJ/kg and melt at 58.37 °C with a latent heat of 165.68 kJ/kg when the encapsulation ratio of the paraffin is 87.5%. The TGA results showed that the SiO2 shells can improve the thermal stability of the microencapsulated paraffin composites due to the synergistic effect between the paraffin and SiO2.