Melamine-formaldehyde microencapsulated n-Tetracosane phase change material for solar thermal energy storage in coating

This work aims to prepare potential solar thermal energy storage coating using melamine-formaldehyde (MF) microcapsules with an n-Tetracosane (n-Tetra) core as phase change material (PCM). The shell material was prepared by reacting melamine with formaldehyde using a two-step process. After centrifuging and drying, these microcapsules were incorporated (0–25 wt%) into an epoxy primer-polyurethane (EP-PU) topcoat system for thermal energy storage applications. The microcapsules were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Polarized Optical Microscopy (POM) & Scanning Electron Microscopy (SEM), respectively. n-Tetra, incorporated in the microcapsule (MF-n-Tetra), has been found to melt at 53.07 °C with the latent heat of melting 134.74 J/g and crystallizes at 48.81 with latent heat crystallization 133.32 J/g. The phase change properties of the coated material were found to increase with the increase in the microcapsule loading. The thermal energy transfer rate was quantified in terms of the time taken by the coated panels to reach an equilibrium temperature of 60 °C. The microcapsule incorporated coatings were also subjected to salt spray analysis to understand any potential effects of phase change material (PCM) loading on the corrosion resistance aspect of the primer-topcoat system. The corrosion resistance was found to increase with microcapsule addition. Thermogravimetric Analysis (TGA) indicated enhanced thermal stability of Tetra in the microcapsule.