Study of the PTC effect in conducting epoxy polymer composites

The thermo-mechanical and electrical properties of conductive epoxy composites are studied and the large decrease of the conductivity as a function of the temperature is analysed in terms of Positive Temperature Coefficient (PTC) effect. Three classes of fillers are used for the materials preparation consisting of polypyrrole (PPy), carbon black and metallic fillers. The PTC mechanism was found to be dependent on the conducting filler, and a new approach was proposed leading to a better understanding of this phenomenon in amorphous filled polymers. The electrical non-linear properties of organic conducting composites as epoxy/PPy have received a particular attention.