Thermal properties of multi-walled carbon nanotube-reinforced polypropylene composites

The thermal conductivity and thermal diffusivity of chemically surface treated multi-walled carbon nanotube (MWCNT) reinforced poly-propylene (PP) composites were measured using 3 omega method in 90 - 320 K and photoacoustic (PA) spectroscopy at room temperature, respectively. Nine kinds of samples were prepared by the melt-blending of PP resins with the addition of 0.1, 0.5, and 2.0 wt% of not treated, nitric acid (HNO3) treated, and potassium hydroxide (KOH) treated nanotube contents, and compression-molded at 180 degrees C into about 0.5 mm thickness composite films using the hot-press. The thermal conductivity was in the range between 0.05 to 0.6 W.m(-1).K-1 and increases as the temperature increases and the CNT concentration increases. By the chemical treatment, the thermal conductivity of 0.5 and 2.0 wt% samples were enhanced about 2 times, however the sample of 0.1 wt% didn't changed. These can be explained qualitatively by the effects of chemical treatment on reinforcing ability for CNTs/polymer composites.