Enhancement in thermal property of phase change microcapsules with modified silicon nitride for solar energy

• A new high thermal conductivity microcapsules were synthesized.
• Thermal behavior was detected by Forward Looking Infra-red System.
• Thermal conductivity is enhanced by 58%.
• Silicon nitride is more economically preferred in promoting the thermal conductivity of phase change materials.

Thermal behavior is one of the most important properties for phase change microcapsules in solar energy storage. Here, a new type of phase change microcapsules was synthesized based on n-octadecane core and polymethylmethacrylate shell supplemented with modified silicon nitride powders, aiming to achieve improvement of thermal property in the phase change materials. SEM micrographs showed that the as-prepared microcapsules have a regular spherical shape with a well-defined core-shell structure. FTIR curves and EDS spectrogram demonstrated that silicon nitride can be well cross-linked with microcapsules after surface modification. In addition, TGA, forward looking infra-red system and DSC (before and after 500 heating and cooling cycles) analyses were performed to investigate the thermal property of the as-prepared microcapsules. The results indicated that the microcapsules have high thermal storage capability, enhanced thermal reliability and stability, and increased thermal conductivity. Especially, the thermal conductivity of microcapsules is enhanced by 56.8% compared with that of the microcapsules without the addition of silicon nitride.