Characterization and thermal performance of microencapsulated sodium thiosulfate pentahydrate as phase change material for thermal energy storage

Abstract

In this work, a novel microencapsulated phase change material based on sodium thiosulfate pentahydrate as core and poly(ethyl-2-cyanoacrylate) as shell was successfully synthesized by interfacial polymerization in a water-in-oil emulsion system. The morphology, microstructure, surface elemental distribution, chemical composition and crystalline structure of the resultant microcapsules were determined by scanning and transmission electron microscopies, energy dispersive spectroscopy, Fourier-transform infrared spectroscopy and X-ray diffraction. Besides, their thermal properties were also investigated systematically by differential scanning calorimetry and thermogravimetry analysis. The results showed that the microcapsules presented almost spherical profiles with a diameter of about 1.0 µm and a well-defined core-shell structure. Meanwhile, the microcapsules possessed phase change temperature of 46.44 °C and latent heat of 107.0 kJ·kg−1 at the core material/monomer mass ratio of 4/2. Due to the protective effect of shell material, the thermal stability of the microcapsules was improved. In addition, the thermal cycling test revealed that the microcapsules had good thermal reliability. Considering the above results, this synthetic technique can be considered as a feasible way to prepare microencapsulated salt hydrates and is expected to extend to the encapsulation of other hydrophilic substances. And the obtained microcapsules have great potential as a solar energy storage material.