Thermal conductivity of carbon nanotube and hexagonal boron nitride polymer composites

This paper investigates the thermal conductivity of nanocomposites of carbon nanotubes (CNT) and hexagonal boron nitride (hBN) polymer composites using a three-dimensional random walk algorithm and effective medium approach (EMA) method. For CNT nanocomposites, the influence of the orientation of CNTs (semi-aligned and randomly-dispersed) on the thermal conductivity was quantified. For hBN nanocomposites, thermal conductivity values were studied in random dispersion of inclusions. Hybrid nanocomposites containing both hBN and CNT were also investigated using a random walk method and experiments. To verify the calculated thermal conductivities, nanocomposite samples were fabricated. Both the modeling and experimental results showed that the concentration of nanoparticulates (random dispersion) in composites increases thermal conductivity up to 170% and 300% for 13.1 vol% CNT and 6.3 vol% hBN, respectively. It was found that the alignment of CNTs may enhance thermal conductivity of CNT composites. For composites with a 13.1 vol% of CNTs, the increase in thermal conductivity of the semi-aligned composites is approximately 210%. However, for hybrid composites with a 3.1 vol% of CNT/hBN (1.55 vol% each), a 290% increase is observed. At 3.1 vol%, thermal conductivity enhancements are 170% and 250% for single-filled composites of CNT and hBN, respectively.