Enhanced Thermal Stability and Degradation Kinetics of Xylitol-Based Phase Change Materials Reinforced with Activated Peanut Shell Biochar and Aluminum Nanoparticles

Phase change materials (PCMs) made with xylitol have large latent heat which is useful in medium temperature energy storage, but they have poor thermal stability and moderate degradation resistance, limiting the high-cyclic operation. The test in this research involved the addition of activated peanut shell-derived biochar (15 wt% and 0.3 wt% and 0.6 wt%) and aluminum nanoparticles (0.3 wt% and 0.6 wt%) to xylitol to promote thermal performance. The composites would be prepared in two stages by dispersion and structural stability, phase transition properties, and degradation kinetics non-isothermal TGA at 20, 25, and 30 C/min would be analyzed by use of XRD and FTIR, respectively and activation energies measured using KAS, FWO and Starinkiso-conversional models. DSC findings indicated that pure PCM contained a melting onset temperature of 85.7 o C, a peak temperature of 94.6 o C and a latent heat mass of 358.4 J/g, PCM +0.3%Al+15%BC and PCM +0.6%Al+15%BC contained latent heats of 345.2 J/g and 332.8 J/g respectively. TGA established insignificant loss of mass below 200C which is a sign that it has thermal reliability within the operating range. Kinetic analysis indicated that pure PCM had average activation energy of about 8390 kJ/mol, PCM+0.3%Al, +15-percent-BC was between 358268.4 kJ/mol, and PCM+0.6%Al, +15-percent-BC was between 188268.7 kJ/mol, which confirmed reduced degradation resistance. The highest thermal stability and degradation delay behavior was observed in the hybrid composite with 0.3% aluminum hence developed materials can be considered promising materials to use in solar thermal storage, waste heat recovery, and medium-temperature energy storage systems.