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The use of phase change materials (PCMs) for thermal storage, thermal management, and thermal insulation has been widespread for many years. Thermal storage systems (TES) based on PCMs can be improved and optimized by adding nanoparticles (NPs) to them. Throughout this study, PCM nanocomposites (NCs) based on paraffin wax (PW) loaded by anatase titania (TiO2) NPs were fabricated and characterized to examine their thermal performance as phase change materials. The as-synthesized TiO2 NPs were obtained by hydrolysis technique and showed a well-defined spherical shape with a diameter in the nanoscale range and a crystallite size ~ 22.75 nm. Throughout the used concentrations of TiO2 NPs, 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.5%, the morphological feature for the PW/TiO2 NCs revealed a good dispersion of NPs in PW. The non-isothermal differential scanning calorimetry (DSC) measurements at a constant heating rate of 10 °C min−1 were used in order to get the melting point (Tm), latent heat of fusion (LH), and latent heat rate (LHR) as a function of TiO2 NP concentrations for the investigated PW/TiO2 NCs. Both LH and LHR values for PW/TiO2 NCs are higher than those obtained for a pure PW sample. The significant enhancement in LH and LHR values for PW/TiO2 NCs was found to be 21.2% and 134.3% in comparison with the pure PW sample, respectively. The thermal stability of the investigated PW/TiO2 NCs was examined using thermal gravimetric (TG) scans. It is found that the thermal stability varies with TiO2 NP concentrations with a non-monotonic trend. At concentrations up to 0.25 mass%, the thermal stability improved. For concentrations over 0.25 mass%, the degradation process became rapid. [ABSTRACT FROM AUTHOR]

A novel composite of SrCO3-microencapsulated palmitic acid (PA) (PA@SrCO3 microcapsules) was prepared an evaluated as a phase-change material through a self-assembly approach. Samples of the material were studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometery (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to determine the composition, crystalloid phase, microstructure, and morphology of the product. Also differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to monitor the thermal behavior of the PA@SrCO3 microcapsules. The data obtained through XRD and FTIR indicated the presence of characteristic peaks of PA and SrCO3, which is only possible when the species do not chemically react with each other. SEM images indicated the PA@SrCO3 microcapsules to be spheres with rough surfaces and average diameters of 1.5–2 µm. TEM images proved the samples as being composed of PA cores encapsulated in a SrCO3 coating. The DSC results showed that the samples had phase-change behaviors, similar to those of pristine PA (melting point = 66.9 °C, latent melting heat = 48.8 J g−1, freezing point = 55.7 °C, latent freezing heat = 43.2 J g−1, at a microencapsulation ratio of 43.92%), and TGA results showed improvements in the thermal stability of PA@SrCO3 microcapsules as opposed to PA, due to the presence of the SrCO3 shell. [ABSTRACT FROM AUTHOR]