Fabrication and performances of new kind microencapsulated phase change material based on stearic acid core and polycarbonate shell

This work is focused on the preparation, characterization and thermal properties of stearic acid/polycarbonate (SA/PC) microcapsule as a new kind of phase change material (PCM) for thermal energy storage, which was prepared by solution casting method. Its morphology, chemical structure and thermal performances were characterized by scanning electron microscope (SEM), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), temperature curves and volume expansion coefficient, respectively. The results show that stearic acid was encapsulated successfully with the maximum mass fraction of 52% without leakage from the composite. The average diameter of microcapsule was found to be 0.50 μm. Two components of the composite PCM, SA and PC, have no chemical reaction and exhibit good compatibility with each other. The melting and freezing temperatures and the latent heats of the microcapsule were measured as 60.0 °C and 51.2 °C, 91.4 J/g and 96.8 J/g, respectively. Iron filings were employed to improve thermal storage and release rates and the rates increased 23% compared with the composite without iron filings. Accelerated thermal cycling test showed that the microcapsules have good thermal reliability after subjected to 1000 thermal cycling because it has similar volume expansion coefficient of polycarbonate. Due to its excellent thermal stability and reliability and simple preparation method, the shape-stabilized SA/PC microcapsule can be considered as candidate PCM for thermal energy storage applications.