Experimental Confirmation of the Existence of the Kapitza Barrier to Thermal Transport in Polymer-Single Walled Carbon Nanotube Composites

Single-walled carbon nanotubes (SWCNTs) were dispersed in sodium dodecylbenzenesulfonate (SDBS) and then subsequently mixed with polystyrene latex followed by partial surfactant removal via Soxhlet extraction. Tall cylindrical samples of 0, 5, 10, and 30 wt% SWCNTs in polystyrene were molded and then measured to determine the thermal conductivity using modulated differential scanning calorimetry (MDSC). The thermal conductivity of each composite increased with temperature until the glass transition temperature was reached. At this point, i.e. at a point where the modulus decreased substantially, the thermal conductivity decreased. This effect is entirely reversible with respect to heating and cooling; i.e. it is not due to tube agglomeration in the melt. This work experimentally demonstrates that the Kapitza resistance affects the thermal conductivity of SWCNT-polymer composites.