Incorporation of graphene nanoplatelets with organic phase change materials – Studies on thermal conductivity enhancement, and thermal and chemical stability

Abstract

Phase change materials (PCMs) have the capability to store energy in form of latent heat, along with exceptional chemical and thermal stability. However, their main limitation lies in their thermal conductivity, which hampers the rate at which energy can be stored and released. In the current work, we have chosen graphene nanoplatelets (GNP) as the thermal conductivity enhancer and organic PCM melting at 21, 30, 35, and 46 °C and a hydrated salt melting at 24 °C. Melt blending technique was used to develop GNP-enhanced PCM, and their chemical and thermal properties were studied. Thermal conductivity was studied in the temperature varying from 25 to 50 °C and we observed a substantial upsurge in thermal conductivity with an upsurge in concentration of GNP. Specific heat was found to increase with an upsurge in concentration of nanoparticles. DSC thermograms depicted a minor upsurge in melting and solidification temperatures and a decline in their latent heat concerning an upsurge in GNP concentration. Subcooling temperature of all pure and GNP-enhanced composites was found to be less than 10 °C. FTIR spectrum peaks designated the presence of physical interaction with the nonappearance of chemical interaction between GNP and PCM. TGA thermograms depicted a minor weight loss till 165 °C and rapid weight reduction in temperature range of 165 – 270 °C which conveys that incorporation of GNP has enhanced thermal stability of PCM. From thermophysical and chemical characterization of pure and GNP-enhanced PCM, we can conclude that GNP-enhanced composites can be used for enhanced heat transfer applications.

Keywords

• Organic phase change material
• Graphene nanoplatelets
• Augmented thermal conductivity
• Thermal stability
• Subcooling temperature