ELECTRORHEOLOGICAL NORMAL STRESS MEASUREMENTS OF POLYMER-SOLUTIONS AND SUSPENSIONS

Normal stress measurement under an electric field is demonstrated as a new method of evaluating ER effects. The measurement was applied to l iquid crystalline polymers, low molecular-weight liquid crystals, poly mer suspension, and aluminum suspension, The normal stress of the liqu id crystalline polymers drastically increased under an electric field at high shear rate, which suggests existence of an elastic network str ucture of the polymer chains. The normal stress of the suspensions als o changed in the field, indicating that interaction of particles resul ts in an increase of both shear stress and normal stress. These change s of the normal stress give additional information which is helpful fo r characterizing ER effects.