MICROSTRUCTURE-CONDUCTIVITY RELATIONSHIP IN CONDUCTING POLYPYRROLE EPOXY COMPOSITES/

Four dispersing methods were used to disperse increasing amounts of Po lypyrrole (PPy), synthesized either via dispersion (PPyd) or suspensio n polymerization (PPys), in an insulating epoxy matrix in order to mak e it electrically conductive. As shown in SEM micrographs and by the p hysical characteristics, PPyd particles exhibit higher density and sma ller particle size than PPys. In addition, optical micrographs of the blends show that PPyd form compact agglomerates and PPys aerated clust ers. It is deduced from conductivity measurements, that energy intensi ve methods or larger particle size (PPys) provide low percolation thre shold, indeed, energy intensive methods, by breaking the PPyd agglomer ates, favour the formation of conductive network of fine particles and therefore lower the PPy concentration at percolation. Similarly, larg er PPys 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. (C) 1 998 Elsevier Science Ltd. All rights reserved.