Effect of PA6T on morphology and electrical conductivity in PA66/PA6T/PPE/multiwalled carbon nanotube nanocomposites

Nanocomposites made of blends of polyamide (PA66), polyphthalamide (PA6T), and poly(2,6-dimethyl-1,4-phenylene ether) (PPE) with multi-walled carbon nanotubes (CNTs) were investigated. At 1 wt% CNT loading, the electrical conductivities of PA66/PA6T/PPE/CNT nanocomposites were around four orders of magnitude larger than those of PA66/PPE/CNT nanocomposites without PA6T. Line mapping images and spot spectrum results from transmission electron microscopy/energy dispersive spectroscopy analysis showed that the continuous phase contained PA66 and PA6T with dispersed PPE domains. Phase inversion was observed as the CNT content of PA6T/PPE/CNT increased. Depending on the polymer composition, alignment of some of CNTs at the interface was observed. Using the wetting coefficient analysis and the Hansen solubility parameter, the morphologies of the nanocomposites and the resulting electrical conductivities were found to be affected by the compatibilizing effect of PA6T on PA66 and PPE as well as the higher affinity of CNTs for PA6T than for PPE or PA66. CNTs were observed to help maintain the integrity of the PA66/PA6T continuous phase by dynamic mechanical analysis.