Fabrication and performance of phase change microcapsules with fatty acid monoglyceride based waterborne polyurethane as the shell

Abstract

AbstractPolyurethane phase change microcapsules (PU‐PCMs) with high encapsulation efficiency are fabricated with ethyl palmitate as the phase change material and fatty acid monoglyceride based waterborne polyurethane as the shell. The compositions and morphologies of microcapsules are characterized by Fourier transform infrared spectrometer (FT‐IR), field scanning electron microscope (FSEM) and laser particle size analyzer. The encapsulation efficiency and phase change performances of microcapsules are investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that PU‐PCMs have smooth surface and spherical shape and the size of about 300 nm. TGA and DSC results show that the encapsulation efficiency of ethyl palmitate in PU‐PCMs prepared with fatty acid monoglyceride is up to 92.3%, which is much higher than that of PU‐PCMs prepared with other diols. The fatty acid monoglyceride based polyurethane prepolymer has better affinity with ethyl palmite than polyurethane prepolymer prepared with other diols, which causes the high encapsulation efficiency of phase change materials. The result of DSC show that the melting enthalpy of fatty acid monoglyceride based PU‐PCMs is 81.6 J g−1and the phase change temperature is 26.75°C. After 200 heating/cooling cycle test, the phase change temperatures and shapes of microcapsules remain unchanged, which show that the microcapsules have good phase change stability. The temperature‐regulating performance and application of the PU‐PCMs in fabricating semi‐transparent temperature‐regulating glass are conducted and investigated. Results of these investigations indicate that PU‐PCMs fabricated from fatty acid monoglyceride show promising applications in heat‐energy storage and temperature‐regulation fields.