Polystyrene microcapsules with palmitic-capric acid eutectic mixture as building thermal energy storage materials

•A eutectic mixture suitable for building applications have been prepared and encapsulated in PS.•Eutectic mixture of natural PCMs have been used for the preparation of MEPCMs.•Palmitic and capric acid are validated at lower temperature than their melting temperatures. In this study, palmitic acid (PA) and capric acid (CA) eutectic mixture was encapsulated in polystyrene (PS) capsules as new latent heat thermal energy storage (LHTES) material for building applications. Eutectic composition ratio of the mixture was determined experimentally. Microencapsulated eutectic mixtures (MEEMs) were prepared in homogenized emulsions in 3 different PS/(PA-CA) weight ratios. The synthesis reaction was found complete according to Fourier Transformed Infrared (FT-IR) Spectroscopy. The physical and physicochemical characteristics, thermal endurance limits and operating stability of MEEMs were investigated through differential scanning calorimetry, thermal gravimetry, and thermal conductivity, particle size distribution analysis, scanning electron microscopy, and polarized optical microscopy techniques. The onsets of melting of MEEMs were measured between 13.5 and 17.1°C as those of crystallization were between 16.9 and 17.9°C. The latent heats of melting of MEEMs were measured between 46.3 and 77.3J/g as those of crystallization were between −45.0 and −73.6J/g. As a result, a eutectic mixture of PA and CA was depicted for building heating cooling applications and successfully encapsulated in PS shell at different weight ratios.