Conductive thermoset composites: PTC effect

Positive temperature coefficient (PTC) materials art: characterised by a reversible metal to insulator transition at a defined temperature Tc. This phenomenon has been widely observed in conducting polymer composite materials such as carbon black / polyethylene compound. From a fundamental point of view, the mechanisms are still not fully understood, especially in conductive filled thermosets, which do not present a large volume expansion compared to a semicrystalline: polymer matrix. The aim of our work consists to study the properties of different conductive: epoxy composites based on mono or biphasic matrix and filled with carbon black or metallic particles. Wt: attempt to contribute to a better understanding of the: electrical non-linear phenomena in such conductive: disordered composite: materials. Analysis of the thermo-mechanical properties, percolation and conduction mechanisms are important and appear to be essential to the understanding of the PTC effect in such composites. Theoretical interpretations of the PTC anomaly will be advanced.