CNT percolation in PS and iPP-g-MA matrices

Even if conductivity results of CNT/polymer nanocomposites are commonly reported in terms of wt%, mainly because of lack of precise CNT density values, percolation is considered to be a volumetric phenomenon. In an attempt to fairly compare conductivity results obtained for systems containing either SWCNTs or MWCNTs dispersed in a given polymer matrix, the percolation threshold values of the various nanocomposites series were calculated in terms of vol% CNT. See ref. [28] for the details of the calculation. 

For the sake of clarity, and in order to compare the various systems. Table 5.1 lists the main results obtained with the different series of nanocomposites prepared. 

As an additional factor, the lower melt viscosity at the compression molding temperature of the iPP-g-MA matrix in comparison with the PS system (about 50 Pa s at 170°C for the former in non-emulsified form vs. well-above 10 Pa s at 180°C for the latter) certainly favors the lowering of the experimental percolation threshold, both for SWCNT and MWCNT nanocomposites (see Table 5.1). A lower melt viscosity of the matrix, indeed, reduces the average CNT-CNT distance and was 

---