Parametric study of intrinsic thermal transport in vertically aligned multi-walled carbon nanotubes using a laser flash technique Original Research Article

The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films synthesized by thermal chemical vapor deposition was measured by a laser flash technique, and shown to be ∼30 mm2 s−1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT films and the individual CNTs were ∼27 and ∼540 W m−1 K−1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube–tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing density was beneficial in increasing the collective thermal conductivity of the VACNT film; however, the increased tube–tube interaction in dense VACNT films decreased the effective thermal conductivity of the individual CNTs in the films. The tip-to-tip contact resistance was shown to be ∼1 × 10−7 m2 K W−1. The study will shed light on the potential application of VACNTs as thermal interface materials in microelectronic packaging.