Rheological Properties of Carbon Black Suspensions in a Silicone Oil

Abstract

Transient shear stresses, steady-state viscosities, and linear dynamic moduli of the furnace carbon black suspensions in a silicone oil were measured as a function of the carbon black concentration. Except for the lowest carbon black concentration, from the transient shear flow experiment structural breakdown is observed at the lower shear rate, whereas at the higher shear rate structural buildup is observed. A crossover point between structural breakdown and structural buildup is decreased with an increase in the carbon black concentration. For the lowest carbon black concentration at the higher shear rate, stress overshooting appeared. Every suspension exhibits shear thickening under steady shear flow, and the critical shear rate corresponding to the onset of steady shear thickening is almost coincident with the shear rate where structural buildup or stress overshooting is first observed. The carbon black suspensions show solidlike viscoelastic behavior under linear responses for dynamic modulus measurements.