Question

# The thermal conductivity of standard SWNT along its length (in W/mk) is:A.3500B.3850C.35000D.None of these

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Hint: SWNT refers to single walled nanotubes. They exhibit thermal conductivity of $2800 - 6000\,W{\text{ }}{m^{ - 1}}{k^{ - 1}}$ for a single nanotube at room temperature.

Complete step by step answer:
-Carbon nanotubes are tubes made up of carbon with diameters typically measured in nanometers.
-The thermal conductivity, as we know lies between $2800 - 6000\,W{\text{ }}{m^{ - 1}}{k^{ - 1}}$It is found to be large.
So, for SWNT, the thermal conductivity measured was nearly $3500\,W{\text{ }}{m^{ - 1}}{k^{ - 1}}$at room temperature for SWNT length of 2.6mm and diameter 1.7mm.
The molecular dynamics (MD) simulations predict the thermal conductivity as high $6600\,W{\text{ }}{m^{ - 1}}{k^{ - 1}}$at room temperature.
-Single walled carbon nanotubes are considered as promising filler materials for improving the thermal conductivity of conventional polymers.
-Hence, the thermal conductivity of SWNT under axial stress is studied by non equilibrium molecular dynamics.
The thermal conductivity is found to increase and then decrease with the tube elongation changing from an axially compressed state to a stretched state.

Hence option A is correct.

Note:
The thermal conductivity of several SWNT has been calculated over a temperature range 100-500 K .In all cases starting from similar values at 100K, the thermal conductivities show a peaking behavior before falling off at higher temperatures.