Hydrophilic modification of carbon nanotube to prepare a novel porous copper network-carbon nanotube/erythritol composite phase change material

Abstract

Carbon nanotube(CNT)-based materials is a promising thermally conductive filler for phase change materials(PCM), while its widely applications are greatly hampered by the hydrophobicity of CNTs. In this work, a novel composite PCM based on hydrophilic modified porous copper network(PCN)-CNT filler and erythritol(Ery) was explored. The hydrophilic modified PCN-CNT filler can be obtained upon heat treatment. During the heat treatment process, defects and oxygen-containing functional groups formed on the surface of CNTs, thus improving the hydrophilicity of CNTs. The optimum heat treatment temperature is determined to be 500°C, at which the adsorptive capacity of the modified filler reaches 88.2% for Ery, larger than 28.2% of the unmodified one. The as-prepared PCN-CNT/Ery composite PCM maintains a similar melting point to that of pure Ery, and its latent heat is as high as 213.2 J g−1. The thermal conductivity of PCN-CNT/Ery composite PCMs increases by 892% and 51% compared with pure Ery and PCN/Ery composite PCM, respectively. Moreover, the PCN-CNT filler could help improve the supercooling of Ery significantly. Besides, the enthalpy loss of the composite PCM was negligible after 20 cycles.