Structures and thermal properties of fatty acid/expanded perlite composites as form-stable phase change materials

Capric acid/expanded perlite (CA/EP) and capric-stearic acid/expanded perlite (CA-SA/EP) composites were prepared. The composite phase change materials (PCMs) were characterized by scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FT-IR). The thermal properties and thermal reliability of the composites were determined by differential scanning calorimetry (DSC), melting-freezing test, polarization microscope equipped with hot stage. Results show that the form-stable composite PCM has an optimal mass ratio of 50% fatty acid. The fatty acid is impregnated into EP by physical attraction. The measured latent heat values of CA/EP composites are 87.3 J/g for the melting process and 89.0 J/g for the freezing process. The corresponding values of the CA-SA/EP are 82.1 J/g and 82.6 J/g, respectively. The DSC, FTIR, and thermal cycling test results show that the thermal reliability of the composite PCMs imperceptibly changes. All of the conclusions indicate that the composites have good thermal and chemical stability.