Microencapsulation and thermal properties of myristic acid with ethyl cellulose shell for thermal energy storage

Encapsulating phase change material (PCM) is an effective way to avoid leakage and prevent contact with external environment. In this work, myristic acid (MA) was used as PCM to store and release latent heat through solid-liquid phase change and ethyl cellulose (EC) was employed as shell to microencapsulate MA for preventing the leakage of melted MA. The novel microencapsulated phase change materials (MPCMs) with MA core and EC shell were fabricated by emulsification-solvent evaporation method. The morphology and particle size of the MPCMs were measured by scanning electronic microscope (SEM), and similar and complete spheres were observed. Chemical structure and crystal phase of MPCMs were analyzed by Fourier transformation infrared spectroscope (FT-IR) and X-ray diffractometer (XRD), finding that EC and MA are well combined by physical action without chemical reaction. Thermogravimetric analyzer (TGA) was used to investigate the thermal stability, and the results revealed that MPPCMs possess excellent thermal stability at working temperature. The thermal cycling tests indicated that the MPCM have excellent thermal reliability. Differential scanning calorimeter (DSC) was employed to analyze the thermal properties of MPCMs. The most satisfying sample is MCPM1 with phase change enthalpy of 122.61 J/g and phase change temperature of 53.32 °C. Hence, the application of the prepared MPCMs in low-temperature solar energy systems has great potential in the future.