Study on the phase change thermal storage performance of palmitic acid/carbon nanotubes composites

After oxidization with the mixed acid of H2SO4 and HNO3, carbon nanotubes (CNTs) were further grafted by γ-(2,3-epoxypropoxy)propyltrimethoxysilane. Then, CNTs, oxidized CNTs and grafted CNTs were respectively dispersed into palmitic acid (PA) matrix to prepare phase change composites at a mass ratio of 1/100. According to the comparative analysis results of the FT-IR spectra, morphology, dispersion and latent heat of the three composites, it is discovered that the composite with grafted CNTs showed the greatest dispersion and tube-matrix adhesion, and thus gained the highest latent heat. It is worth mentioning that the composite with grafted CNTs demonstrated a more favorable latent heat and a 34.1% enhancement of thermal conductivity in comparison with PA. Moreover, the composite with grafted CNTs kept homogeneous after 100 times of melting and freezing, and the retention rate of latent heat can be as high as 98.5%.