Preparation of Phase Change Microcapsules with the Enhanced Photothermal Performance.

The performance of solar-thermal conversion systems can be improved by incorporation of encapsulated phase change materials. In this study, for the first time, Crodatherm 60 as a phase change material (PCM) was successfully encapsulated within polyurea as the shell supporting material. While preparing the slurry samples, graphite nanoplatelet (GNP) sheets were also incorporated to enhance the thermal and photothermal properties of the prepared materials. The morphology and chemical properties of these capsules were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrum, respectively. The results show the spherical-like and core-shell structure of capsules with an average diameter size of 3.34 μm. No chemical interaction was observed between the core and the supporting materials. The thermal characteristics of the microencapsulated PCMs (MEPCMs), analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), indicate that the prepared samples with 0.1 weight percentage of GNP possess the latent heat of 95.5 J/g at the phase transition temperature of about 64 °C. Analyzing the rheological properties of the prepared slurry with 16 wt % of MEPCMs proves that the prepared material meet the requirements given by the heat transfer applications. The thermal storage capacity, good thermal stability, and improved photothermal performance of the prepared material make it a potential candidate for using in direct absorption solar thermal applications.