Capric acid phase change microcapsules modified with graphene oxide for energy storage

To improve the efficiency of energy, phase change microcapsules with capric acid as core material and urea–formaldehyde resin modified by graphene oxide (GO) as shell material were synthesized by in situ polymerization. The particle characteristics, chemical structure, thermal conductivity and thermal stability of capric acid phase change microcapsules were studied by environmental scanning electron microscopy, laser particle size analyzer, Fourier transform infrared spectroscopy, thermal conductivity meter and differential scanning calorimeter. The results showed that the surfaces of MEPCMs–0.3%GO, MEPCMs–0.6%GO and MEPCMs–0.9%GO are relatively smooth compared with MEPCMs, but the surface smoothness of capric acid phase change microcapsules will decrease with the increase in graphene oxide dosage. The inflection point of encapsulation ratio of capric acid phase change microcapsules occurs in the 0.6% dosage of graphene oxide. Compared with MEPCMs, thermal conductivity of MEPCMs–0.9%GO increased by 75.1%, 64.2% and 73.6% at 20 °C, 30 °C and 40 °C, respectively. In the thermal cycle experiment, capric acid phase change microcapsules possess the better heat stability. Because graphene oxide can be stably buried or embedded in the shell material of urea–formaldehyde resin and forms heat transfer channels on the surface and inside of urea–formaldehyde resin, the thermal properties of capric acid phase change microcapsules can be improved.