ANISOTROPIC THERMAL DIFFUSIVITY OF ALIGNED MULTIWALLED CARBON NANOTUBE ARRAYS

摘要

This work employs a photothermoelectric technique to measure the anisotropic thermal diffusivity of an aligned multiwalled carbon nanotube array. A modulated laser beam incident to the front surface of the sample creates a thermal wave which is detected by a fast responding thermocouple formed between the back surface of the sample and the tip of a sharp metallic probe. The anisotropic thermal diffusivity values are obtained by fitting the radial and frequency dependent thermal signals with an anisotropic heat conduction model. The room temperature thermal diffusivity measured perpendicular to the alignment direction is 0.246x10~(-5) m~2/s, an order of magnitude smaller than thermal diffusivity along the CNTs alignment direction 4.4x10~(-5) m~2/s. However, the thermal diffusivity of the aligned multiwalled CNT is two orders of magnitude smaller than expected for an individual multiwalled CNT.