ELECTRORHEOLOGICAL NORMAL STRESS MEASUREMENTS OF POLYMER SOLUTIONS AND SUSPENSIONS

Abstract

Normal stress measurement under an electric field is demonstrated as a new method of evaluating ER effects. The measurement was applied to liquid crystalline polymers, low molecular-weight liquid crystals, polymer suspension, and aluminum suspension. The normal stress of the liquid crystalline polymers drastically increased under an electric field at high shear rate, which suggests existence of an elastic network structure of the polymer chains. The normal stress of the suspensions also changed in the field, indicating that interaction of particles results in an increase of both shear stress and normal stress. These changes of the normal stress give additional information which is helpful for characterizing ER effects.