Thermal Conductivity of Single-Walled Carbon Nanotubes under Axial Stress

The thermal conductivity of single-walled carbon nanotubes (SWCNTs) under axial stress is studied by nonequilibrium molecular dynamics simulation. The thermal conductivity is found to increase and then decrease with the tube elongation changing from an axially compressed state to a stretched state. The phonon density of states of the systems is analyzed to elucidate the variation of heat conduction with respect to the stress in CNTs. The primary peak of the phonon spectrum shows a blue shift or red shift as the SWCNT is compressed or stretched. These shifts correspond to the change of the elasticity coefficient of the CNTs. The variation trend of primary peak height of radial phonon spectra with axial strain is similar to that of the thermal conductivity, which indicates that the radial phonon modes, especially the high-frequency modes, play a dominant role in the heat conduction mechanism of CNTs.