Microcapsules of n-dodecanoic acid/melamine-formaldehyde with enhanced thermal energy storage capability for solar applications

Abstract

A new bio-based microencapsulated phase change material (MEPCM) was synthesised by an in situ polymerisation method, and its thermal energy storage properties were experimentally studied. Bio-based n-dodecanoic acid with a high heat storage capacity was encapsulated by a melamine-formaldehyde (MF) polymeric shell. The MEPCM was characterised using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermal conductivity analysis (TCA). The microcapsules had a perfectly spherical morphology with a core–shell microstructure. The MEPCM was chemically stable, and its crystallinity was unaltered. Dodecanoic acid encapsulated by the MF shell exhibited a high thermal energy storage capability of 99.3% and was observed to melt at 41.8 °C with a decent enthalpy of 41.7 kJ/kg. The prepared microcapsules were thermally stable up to 165.02 °C, which were also observed to be leak-proof well above the phase transition temperature. Furthermore, the thermal reliability of the MEPCM was good after 1000 thermal cycles. Overall, the MEPCM was a viable candidate for medium-temperature thermal energy storage applications.