A preliminary investigation of conductive immiscible polymer blends as sensor materials

This paper discusses the feasibility of the application of conductive immiscible polymer blends as sensor materials for detection of organic liquid solvents. Immiscible polymer blends of polypropylene (PP), nylon 6 (Ny6) and carbon black (CB) have been used to produce a series of electrically conductive filaments by a capillary rheometer process. In these immiscible blends, PP serves as a semi-crystalline matrix and Ny6 as the semi-crystalline dispersed phase, The enhancement of conductivity in these blends is due to the attraction of CB to Ny6 and localization of CB particles at the PP/Ny6 interface, giving rise to conductive networks, The de electrical resistivity of extruded filaments, produced at different shear levels, is found to be sensitive to various organic liquid solvents. The shear rate at which the filaments are produced has an important effect on the PP/Ny6/CB filament's sensitivity. The compositions studied were close to the double-percolation structure believed to perform best as sensor materials. In addition, it seems that the PP/Ny6 interface plays a major role in the sensing process. Liquid contact/drying cycling of the filaments indicates stabilization of the sensitivity change making the sensing process reversible.