Preparation, Microencapsulation, and Characterization of CA-PA Eutectic (PCM) as Thermal Energy Storage System

Abstract

This work is focused on the synthesis of a eutectic mixture of capric and palmitic acid (CA-PA) as phase change material (PCM) for human comfort temperature (25±1oC) and microencapsulation with crosslinked-polystyrene using emulsion polymerization. Chemical interactions of shell material with PCM and morphology of prepared microencapsulated PCM (MEPCM) were examined using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) respectively. The melting (25.53oC) enthalpy based on differential scanning calorimetry (DSC) measurement was found 134.61 J·g-1 while the same for MEPCM (25.10oC) was 96.98 J·g-1. The encapsulation ratio estimated based on DSC analysis was found to be 72.05%. The thermal durability of MEPCM was investigated using thermogravimetric analysis (TGA). Degradation of MEPCM took place in three different steps with 69.10% evaporation loss of PCM which supported the DSC results. Particle size distribution (PSD) ranged between 3.3 μm and 23.6 μm. Hence, MEPCM of CA-PA eutectic mixture with their large latent heat storage ability with higher thermal stability would be useful in energy storage applications.

Keywords: Eutectic mixture, phase change materials, microencapsulation, emulsion polymerization, thermal energy storage