Preparation and Thermal Properties of Grafted CNTs Composites

Oleylamine (G18) and octanol (G8) were grafted onto the surfaces of the multi-walled carbon nanotubes (CNTs). The grafted CNTs were dispersed into palmitic acid (PA) and paraffin wax (PW) to prepare phase change composites. The heat storage/retrieval experiments showed that the composites kept stable after repeating melting and solidification for 80 times. The structure of the G18-CNT/PA and G8-CNT/PA was homogenous compared with the pristine CNT (P-CNT)/PA. The latent heat capacity (L-s) of solid liquid phase change of G18-CNT/PW was higher than that of PW while those of the G8-CNT/PW and P-CNT/PW were lower than that of PW. Compared with PA, all PA based composites with both P-CNTs and grafted CNTs decreased L-s evidently. The L-s values of G18-CNT composites in both matrices were higher than that of the counterparts of G8-CNT. The thermal conductivities of all the PA based composites in the study were higher than that of PA, as well as those of all the PW based composites. However, the thermal conductivities of the G18-CNT composites in both matrixes were lower than those of the G8-CNT composites in both matrixes at all measured temperatures.