Preparation and characterization of palmitic acid/graphene nanoplatelets composite with remarkable thermal conductivity as a novel shape-stabilized phase change material

This paper mainly concentrates on the shape stability and thermal conductivity of palmitic acid (PA)/graphene nanoplatelets (GNPs) composite phase change material (PCM). The impregnation method was done to prepare shape stabilized PCM with GNPs for three different specific surface areas of 300, 500 and 750 m(2)/g. The maximum mass percentage of PA absorbed by GNPs was 91.94 wt% without leakage of PA in molten state as proven by dropping point test. Scanning electron microscope (SEM), Transmission electron microscopy (TEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscope (FTIR) were applied to determine microstructure and chemical structure of palmitic acid (PA)/GNPs composites, respectively. Differential scanning calorimeter (DSC) test was done to investigate thermal properties which include melting and solidification temperatures and latent heats. The thermogravimetric analyzer (TGA) results show that thermal stability of PA was increased by using GPNs. The thermal reliability and chemical stability of composite PCM were determined by cycling test for 2500 cycles of melting and freezing. The improvement of thermal conductivity was calculated to be 10 times that of the PA. As a result, due to their acceptable thermal properties, good thermal reliability, chemical stability and great thermal conductivities, we can consider the prepared shape-stabilized composites as highly conductive PCMs for thermal energy storage applications. (C) 2013 Elsevier Ltd. All rights reserved.