Linear viscoelasticity of semiconducting polyaniline based electrorheological suspensions

A dry-base electrorheological (ER) fluid was prepared by dispersing synthesized semiconducting polyaniline (PANI) particles into silicone oil, and its viscoelastic properties were investigated under applied electric fields using a rotational rheometer. Within the linear viscoelastic region, the ER fluid was observed to be elastic, due to columnar structure of PANI particles sustaining the deformation. Its rheological functions (G' and G") were interpreted based on the dimensional analysis, and they showed roughly linear electric-field dependence of the dimensional collapse of the viscoelastic behavior with frequency suggesting that the interactions between highly irregular particles are saturating even at these relatively low values of the dielectric mismatch. Furthermore, the recovery percentage obtained from the creep and recovery experiments increased with applied electric fields. (C) 2004 Kluwer Academic Publishers.