Effect of multiwalled carbon nanotube (M-CNT) loading on M-CNT distribution behavior and the related electromechanical properties of the M-CNT dispersed ionomeric nanocomposites

The multiwalled carbon nanotube (M-CNT)/Nafion nanocomposites were prepared by a method of solution casting and then characterized by using X-ray diffraction (XRD), thermogravimetry/differential scanning calorimetry (TG/DSC), scanning and transmission electron microscopy (SEM/TEM) to evaluate the effect of M-CNT loading in the range of 0 to 7 wt.% on M-CNT distribution behavior and the related electromechanical properties of the composites. The M-CNT bundles induced by the Nafion polymer was uniformly distributed for the 1 wt.% M-CNT/Nafion nanocomposites, exhibiting the highest elastic modulus and improved electromechanical properties. However, further M-CNT loading caused a heterogeneous distribution of M-CNT bundles and a negative impact on the connectivity within the Nafion matrix, giving rise to poor actuation properties. An appropriate equivalent circuit model was proposed to evaluate the effect of capacitance and resistance of M-CNT/polymer nanocomposites. In conclusion, it is found that the actuation properties of the nanocomposites are primarily governed by the M-CNT distribution behavior within the polymer matrix.