Percolation network of polypyrrole in conducting polymer composites

Polypyrrole-bisphenol A based epoxy composites have been prepared using different amines as hardener systems. The conductivity was studied as a function of the PPy content and compared to carbon black/epoxy composites. The insulator-to-conductor transition was analysed according to the percolation theory and a model was proposed to fit experimental data of composite resistivity. Direct observation and image analysis of the conducting composite allowed the determination of the fractal dimension of the polypyrrole network D and the backbone DB, which were found not to be constant with the filler concentration and were compared with the scaling theory prediction.