Electrorheological characterization of semiconducting polyaniline suspension

Electrorheological (ER) properties of polyaniline suspensions in silicone o il with various experimental conditions were investigated. These suspension s exhibit dramatic changes in their rheological properties which are caused by the formation of particle chain structures induced by an applied electr ic field. Polyaniline was synthesized by the chemical oxidation of aniline with ammonium peroxysulfate. This study examined the effects of electric fi eld, volume fraction, polymerization temperature and operation temperature on the ER properties of polyaniline suspensions in silicone oil. Rheologica l measurements were carried out by using a rotational rheometer with a high voltage generator in both controlled shear stress and shear rate modes. Ex perimental results showed that the ER properties were enhanced by increasin g the volume fraction and electric field and were independent of the operat ing tempertures. The best ER properties were also obtained by using polyani line particles synthesized at -10 degrees C, and these had a conductivity o f similar to 10(-10) S/cm.