Synthesis and characterization of microencapsulated paraffin with titanium dioxide shell as shape-stabilized thermal energy storage materials in buildings

• The microencapsulated paraffin with TiO2 shells was prepared by a sol–gel process.
• Chemical structure, crystalloid phase and microstructure of the MPCMs were analyzed.
• Thermal properties and stability of the MPCMs were investigated.
• The TiO2 shells can improve thermal stability of the MPCMs.

Microencapsulated paraffin with titanium dioxide (TiO2) shells as shape-stabilized thermal energy storage materials in buildings were prepared through a sol–gel process. In the core–shell structure, the paraffin was used as the phase change material (PCM), and the TiO2 prepared from tetra-n-butyl titanate (TNBT) acted as the shell material. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine the chemical structure, crystalloid phase and microstructure. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). The FT-IR and XRD results presented that characteristic peaks of both paraffin and TiO2 can be observed in the microencapsulated paraffin with the TiO2 shells. The DSC results indicated that the microcapsules exhibited similar phase change characteristics as those of pure paraffin, and the typical ones melt at 58.8 °C with a latent heat of 161.1 kJ/kg and solidify at 56.5 °C with a latent heat of 144.6 kJ/kg when the microencapsulation ratio is 85.5%.