Facile and safety synthesis of highly loaded phase change microcapsules with paraffin/butyl stearate core and their feasible application in polymer composite.

Highly paraffin/butyl stearate-loaded phase change microcapsules were synthesized by cosolvent-free interfacial polymerization using low-toxicity dicyclohexylmethane-4, 4′-diisocyanate as the shell material. The formation of the microcapsules and their distribution in the epoxy were studied by means of optical microscope and scanning electron microscopy, respectively. The chemical composition of microcapsules was confirmed through Fourier transform infrared spectrometer. And the phase change properties, thermal stability and cyclic thermal stability of microcapsules and their thermal insulation properties and thermal response behavior in the epoxy were investigated through differential scanning calorimetry, thermogravimetric analysis, leakage prevention test, thermal conductivity test and temperature response experiment, respectively. The synthesized spherical microcapsules have distinct core-shell structure with an average diameter of 220.6 μm. The microcapsules achieve an encapsulation rate of 78.5%, with the melting enthalpy and the crystallization enthalpy being 148.5 J/g and 159.2 J/g, respectively. They not only exhibit good thermal stability and cyclic thermal stability, but also can disperse in the epoxy uniformly and combine with the epoxy tightly. In addition, compared with the pure epoxy, the epoxy containing 15 wt% microcapsules experiences a 10.1% decreases in thermal conductivity and a 55.4% increase in delayed time of temperature rise/fall, showing an excellent temperature regulation ability. [Display omitted] • HMDI was employed as the shell material due to low toxicity. • The microcapsules with core-shell structure achieve an encapsulation rate of 78.5%. • High enthalpy microcapsules exhibit 99.2% of heat-storage efficiency. • The microcapsules have high thermal stability, reliability and applicability. • 15 wt% microcapsules increase the time delay by 55.4% for temperature rise/fall. [ABSTRACT FROM AUTHOR]