Polyaniline/clay as nanostructured conductive filler for electrically conductive epoxy composites. Influence of filler morphology, chemical nature of reagents, and curing conditions on composite conductivity

Electrically conductive composites based on epoxy resin, anhydride hardener and polyaniline (PANI) as conductive filler have been formulated and characterized. Standard PANI (Pani) and PANI/clay (PANICN) nanofillers were used to study the impact of filler morphology on the electrical properties of composites. Clay was used as a nanostructured template to increase the PANI aspect ratio (ratio of length to diameter or thickness). The use of PANICN reduces the electrical percolation threshold of composites from 4.5 vol.% to 1.3 vol.%. Moreover, the conductivity of composites containing PANICN is improved to values superior to 10−3 S/cm. The effects of reagents and curing conditions were also evaluated. It was demonstrated that a classical alkaline curing accelerator, such as imidazole, exhibits chemical incompatibilities with the PANI conductive form, resulting in less conductive composites. Substituting the classical alkaline curing accelerator with a cationic accelerator, such as a Lewis acid, is a promising alternative to obtain conductive epoxy composites with a low content of PANI.