The effect of compressive stress on the electrically resistivity of poly(vinylidene fluoride)/polypyrrole blends

Variation of the electrical resistivity under repeated loading–unloading compressive cycles of poly(vinylidene fluoride) (PVDF)/polypyrrole (PPy) blends prepared by solution-casting has been investigated. The insulator–conductor transition of the PVDF/PPy blends was very sharp and the percolation threshold was found to be below 4 wt%. PVDF/PPy blends exhibits a decrease in the electrical resistivity with the applied compressive stress due to the formation of new conducting pathways. Electromechanical response was dependent of PPy amount and the maximum sensitivity was obtained for a blend with a PPy content of 9 wt%, for which the electrical resistivity drops by two orders of magnitude, e.g. from 108 to 106 Ω cm. The electrical resistivity variation during compressive stress cycles, the reproducibility and the reversibility makes this system a suitable material for the development of pressure sensors.