STRUCTURE AND ELECTRICAL-PROPERTIES OF POLYPYRROLE THERMOPLASTIC ELASTOMER BLENDS

Conducting thermoplastic elastomer blends have been synthesised by deposition of polypyrrole in styrene-butadiene-styrene (SBS) block copolymers containing various amounts of ferric chloride (FeCl3). These blends have phase-segregated morphology with preferential deposition of polypyrrole in one of the domains as confirmed by structural investigations using optical microscopy, X-ray diffraction and infrared spectroscopy. The electrical resistivity (rho) for these blends shows a sharp transition in the region of 273 K and is sensitive to small mechanical deformations both in compression and extension modes. The dependence of rho on mechanical stress (P) follows a power law of the type rho is-proportional-to P(n), where n has a value between 3 and 4. These various findings have been explained on the basis of a phase-segregated morphology having highly conducting domains separated by a semiconducting/insulating matrix, together with non-linear conduction processes for charge transport in such heterogeneous materials.