Chemical sensing materials based on electrically‐conductive immiscible polymer blends

Two families of electrically‐conductive immiscible polymer blends were studied as liquid sensing materials for an homologous series of alcohols. The systems studied include: multiphase matrices [containing carbon black (CB)] consisting of either polypropylene or high‐impact polystyrene as the major phase and thermoplastic polyurethane as the minor dispersed phase; and polyaniline (PANI) dispersed within a polystyrene matrix. Extruded filaments, produced by a capillary rheometer at various shear‐rate levels were used in the sensing experiments. The electrical resistance of these filaments was selectively sensitive to the various alcohols. Moreover, the responses displayed by these filaments are reproducible and reversible. The sensing behaviour of these blends is determined by the nature of the blend components, the blend composition and the processing conditions. An attempt is made to identify the dominant mechanisms controlling the sensing process in CB‐containing immiscible polymer blends and PANI‐containing blends. In addition, the sensing performances of these blends are compared in the light of their sensing mechanisms.