Advanced bimodal polystyrene/multi-walled carbon nanotube nanocomposite foams for thermal insulation

We developed an advanced bimodal polystyrene (PS)/multi-walled carbon nanotube (MWCNT) nanocomposite foam with a very low thermal conductivity of 30 mW/m-K without using any insulation gas. The MWCNTs significantly decreased the radiative thermal conductivity of the foams with the high infrared (IR) absorption capability and increased the optimal expansion ratio of the foams to minimize the total thermal conductivity. The radiative blocking effect of MWCNTs was quantitatively modeled by calculating the IR absorption index of the unfoamed nanocomposites and calculating the IR extinction coefficient of the foamed nanocomposites. In addition, a theoretical model to analyze the optimal expansion ratio in synergistic bimodal nanocomposite foam was developed for the first time. The calculated values were in good agreement with the experimental data to verify the superior heat-blocking characteristics of the MWCNTs in the bimodal cellular morphology. (C) 2017 Elsevier Ltd. All rights reserved.