Influence of carbon nanotubes localization and transfer on electrical conductivity in PA66/(PS/PPE)/CNTs nanocomposites

Abstract

The localization and transfer of carbon nanotubes (CNTs) in PA66/(PS/PPE)/CNTs nanocomposites were investigated using several methods including TEM/EDS techniques, surface energy and wetting coefficient calculations, electrical conductivity measurements, and rheological analysis. The CNTs were found to be dispersed preferentially in the polyamide 66 (PA66) phase and not in the miscible polystyrene (PS)/poly(phenylene ether) (PPE) blend phase because CNTs have a higher affinity for PA66. The electrical conductivity of the PA66/(PS/PPE)/CNTs nanocomposites significantly increased compared to the PA66/CNTs nanocomposites at the same CNT loading. The nanocomposites were prepared with three different compounding procedures. The nanocomposites prepared with sequence III (premixing PS/PPE and CNTs, and then blending the (PS/PPE)/CNTs with PA66) yielded a better CNT dispersion that resulted in a higher electrical conductivity. The CNT dispersion was determined by TEM and rheological analysis. Additionally, the nonlinear-linear viscoelastic ratio (NLR) was used to quantify the degree of CNT dispersion. Because the CNTs initially dispersed in the unfavorable PS/PPE phase were transferred as individual rods into the preferred PA66 phase during the second step of compounding sequence III, the nanocomposite prepared with sequence III had a higher NLR value, that is, a better CNT dispersion compared to the other nanocomposite prepared with different compounding sequences.