Electrorheological properties of phosphoric ester cellulose electrorheological suspensions with activation of dispersed particles

The electrorheological (ER) behavior of activated ER suspensions in silicone oil of phosphoric ester cellulose powder (average particle size : 17.77 mum) was investigated at room temperature with electric fields up to 2.5 kV mm(-1). For increasing ER effect of ER suspensions, activating effect of dispersed particles, phosphoric ester cellulose, on ER activity was studied. Anhydrous ER suspensions based on phosphoric ester cellulose particles made from cellulose treated in chemical solution of 2 M phosphoric acid and 4 M urea, heated at 150degreesC and crushed were measured. After activating the dispersed particles in anhydrous ER suspensions at 120degreesC, analysis of the dispersed phosphoric ester cellulose particles was made. ER properties of ER suspensions such as dielectric constant, current density, electrical conductivity, and rheological properties were studied. Activating of dispersed particles had large influence on ER activities of anhydrous ER suspensions based on phosphoric ester cellulose. With activation time, particle size, and number of dispersed particles per unit volume, electrical properties, dynamic yield stress on electric field, initial apparent viscosity (eta(0)), and ER effect (tau(A)/tau(0)) of phosphoric ester cellulose ER suspensions increased at 120degreesC.