Switching effect in pressure deformation of silicone rubber/polypyrrole composites

Conductive silicone rubber/polypyrrole composites were prepared by cast molding of polymer matrix components and chemically synthesized polypyrrole (PPy). Composites contained from 2.2 to 8.5 vol.% of PPy. The sigmoid dependence of the conductivity of original uncompressed sample on the filler was found and PPy percolation threshold concentration lower than 4 vol.% was estimated. Electrical conductivity of silicone rubber/polypyrrole composites in pressure deformation showed a steep decrease more than five orders of magnitude to values corresponding to an insulator. This "switching effect" had a good reproducibility, which suggests a possible use of this material in microelectronics. (C) 2004 Elsevier B.V. All rights reserved.