Tetradecyl octadecanoate phase change microcapsules incorporated with hydroxylated boron nitrides for reliable and durable heat energy storage

In this paper, phase change microcapsules with excellent performance and stability were synthesized by interfacial polymerization by using tetradecyl octadecanoate (TO) as the core material, isophorone diisocyanate as the shell-forming monomer and modified boron nitride (BN) as the thermal conductive filler. The micro morphologies of unmodified BN, modified BN and different phase change microcapsules   were observed by an optical microscope and a scanning electron microscope, and their chemical structures were analyzed through a Fourier transform infrared spectrometer. Meanwhile, the phase change behavior, thermal stability, thermal cycle stability and thermal conductivity of phase change microcapsules were investigated by differential   scanning   calorimetry, thermogravimetric analysis and thermal conductivity tests. Finally, their exudation stability was tested through leakage experiments. The results show that the spherical TO microcapsules incorporated with modified BN with core-shell structure not only feature a great heat storage capacity (over 150 J/g) and a high encapsulation rate (66.53 %), but also possess excellent thermal stability and thermal cycle stability. After 300 thermal cycles, the phase change peak temperature and the phase change enthalpy value fluctuate within 1.23 °C and 13.76 J/g, respectively. Compared with that of microcapsules without BN, the thermal conductivity of microcapsules incorporated with 3 wt% modified BN increases to 0.1154 W/m·K by 7.95 %. In addition, the microcapsules incorporated with modified BN exhibit prominent exudation stability which enables them to remain intact without leakage at 100 °C for 8 h.