Experimental Study of the Thermal Properties of Microencapsulated Palmitic Acid Composites with CuCO3 Shell as Thermal Energy Storage Materials

Abstract

A novel microencapsulated phase change material (PCM) with a Palmitic acid (PA) core and Copper (II) carbonate (CuCO₃) shell was successfully fabricated through a self‐assembly method. Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to determine the chemical compositions, crystalloid phase, microstructure and morphology of PA@CuCO₃ microcapsules, respectively. The thermal properties and thermal stability of microcapsules were determined by differential scanning calorimetry (DSC) and a thermogravimetric analysis (TGA). The XRD and FT‐IR results indicated the presence of all of the characteristic peaks of PA and CuCO₃ and proved that no chemical reaction had occurred between them. The SEM images showed a regular spherical morphology with rough surfaces for the PA@CuCO₃ microcapsule with average diameters ranged from 1.5 to 2 μm, and the TEM image confirmed the PA core to have been well encapsulated by CuCO₃. In the DSC analysis results, the microcapsules indicated similar phase change behaviors as those of pristine PA, and the typical samples were melted at 66.9 °C with a latent heat of 48.85 J/g and frozen at 55.7 °C with a latent heat of 43.29 J/g for a microencapsulation ratio of 43.92%. TGA analyses indicated that the thermal stability of the PA was further improved due to the protection of the PA core encapsulated by the CuCO₃ shell.