Preparation and Thermal Performance of Microcapsules with Graphene/n-Octadecane as Core Material

Novel microcapsules containing graphene/n-octadecane as core material and melamine-urea formaldehyde polymer as shell material were prepared by emulsion polymerization with styrene maleic anhydride copolymer (SMA) used as emulsifier. The effects of graphene on the properties of n-octadecane microcapsules were studied. Surface morphology, crystallography and thermal properties of microcapsules were characterized and analyzed by using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-Ray diffraction (XRD), thermal constant Hot Disk analyzer, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The results indicate that the microcapsules are spherical and have relatively smooth surface. The particle size of microcapsules is about 1 30 mu m. In addition, the morphology of microcapsules has no obvious change the with 0.1 g graphene addition. Too much graphene intensifies the reunion of microcapsules. XRD shows that graphene in microcapsules does not change the crystallization peak position of microcapsules, which is good for the practical application of the microcapsules. Heat enthalpy and encapsulation of microcapsules decrease with the increase of graphene addition, but the supercooling phenomenon of core material has been observably improved. Heat transfer performance of microcapsules is markedly improved due to graphene. Thermal conductivity coefficient of microcapsules is 0.092 W.m(-1).K-1 with 0.2 g graphene addition, which is enhanced by about 51%, compared with the pure microcapsule. It illustrates that graphene may improve the heat transfer performance of traditional phase change microcapsules and promoted the application performance of phase change microcapsules.