Thermophysical 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 polypropylene (PP) composites were measured using the 3ω method in the temperature range of 90–320K 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 mass% of non-treated, nitric acid (HNO3)-treated, and potassium hydroxide (KOH)-treated nanotube coIntents, and compression-molded at 180◦C into about 0.5mm thickness composite films using the hot-press. The measured thermal conductivities are in the range from 0.05 to 0.6W·m−1 ·K−1 and increase as the temperature increases and the CNT concentrations are increased. By the chemical treatment, the thermal conductivity of 0.5 and 2.0 mass% samples were enhanced by about a factor of two; however, the sample of 0.1 mass% did not change. This can be explained qualitatively by the effects of chemical treatment on the reinforcing ability for CNTs/polymer composites.