Thermal transport in multiwall carbon nanotube buckypapers

A steady-state electro-Raman-thermal (SERT) technique is developed to characterize the thermal transport in multiwall carbon nanotube (MWCNT) buckypapers. This SERT technique involves steady-state joule heating of a suspended sample and measuring its middle point temperature based on Raman shift intensity. The thermal conductivity is determined from linear fitting of the temperature against heating power. Combined with the transient-electro-thermal technique, the thermophysical properties of two MWCNT buckypapers are characterized as 1.19 and 2.92 W/(m K) for thermal conductivity, 3.65×10−63.65×10−6 and 7.58×10−6 m2/s7.58×10−6 m2/s for thermal diffusivity, 459 and 543 kg/m3 for density. Detailed discussion and analysis are provided about the uncertainty of the SERT technique and its capacity for measuring wires down to sub-μm length. The low thermal conductivity of the buckypaper indicates its thermal transport is determined by the thermal contact resistance between MWCNTs. These contact points feature low thermal conductance. The mean distance between two adjacent contact points is estimated in the order 45–450 μm and 93–933 μm for the two samples, indicating low-density contacts within the buckypaper.