Four dispersing methods were used to disperse increasing amounts of Polypyrrole (PPy), synthesized either via dispersion (PPy d) or suspension polymerization (PPy s), in an insulating epoxy matrix in order to make it electrically conductive. As shown in SEM micrographs and by the physical characteristics, PPy d particles exhibit higher density and smaller particle size than PPy s. In addition, optical micrographs of the blends show that PPy d form compact agglomerates and PPy s aerated clusters. It is deduced from conductivity measurements, that energy intensive methods or larger particle size (PPy s) provide low percolation threshold. Indeed, energy intensive methods, by breaking the PPy d agglomerates, favour the formation of conductive network of fine particles and therefore lower the PPy concentration at percolation. Similarly, larger PPy s particles are arranged in clusters allowing a more homogeneous distribution of PPy particles in the resin and a smaller percolation threshold. The microstructure of the blends are observed by TEM.
Посилання на статтю:
Microstructure–conductivity relationship in conducting polypyrrole/epoxy composites / C. Cassignol, M. Cavarero, A. Boudet, A. Ricard // Polymer. – 1999. – N 40. – P. 1139–1151.