Preparation, characterization, and thermal properties of the microencapsulation of a hydrated salt as phase change energy storage materials

Microcapsules loaded by disodium hydrogen phosphate heptahydrate (Na2HPO4·7H2O) were prepared by means of the suspension copolymerization-solvent volatile method, with modified polymethylmethacrylate (PMMA) as coating polymer under the conditions of various organic solvents. The formation of the microencapsulated phase change materials (MEPCMs)-PMMA/Na2HPO4·7H2O was investigated and analyzed. The morphology of the resultant materials was characterized by using scanning electron microscope (SEM) and phase contrast microscope. Its final composition was confirmed by the Fourier transformation infrared (FT-IR). Thermo gravimetric analyzer (TGA) and differential scanning calorimetry (DSC) were adopted to reveal its thermal stability and thermal properties. Results indicated that the materials owned improved subcooling degree and good thermal properties, enabling the materials to be one promising phase change materials for thermal energy storage.

► Phase change point and fusion heat of samples are about 51 °Cand 150 J/g respectively.
► DSC results indicated the core material is not Na2HPO4·12H2O but Na2HPO4·7H2O.
► Encapsulation takes a significant role in reducing subcooling degree.