Rheological behavior of highly concentrated aqueous silica suspensions in the presence of sodium nitrate and polyethylene oxide

Abstract

The shear flow properties of aqueous silica suspensions at different solids loading in the presence of polyethylene oxide (PEO) and added salt (NaNO3) have been investigated. Particular attention is given to the evaluation of the role of electrolyte concentration, pH, and polymer concentration in viscosity reduction. The variation of the rheological properties with shear rate, solids loading, particle size, pH, electrolyte concentration, PEO concentration, and its molecular weight are discussed. The viscosity of the silica suspension was determined to be a decreasing function of the particle diameter and at 54% volume, the effect of particle size was scaled using Peclet number and relative viscosity of the suspension (hard sphere scaling). The flow properties of silica suspensions are highly affected by the pH of the suspending media and concentration of the added salt. At a fixed electrolyte concentration, the viscosity decreases by increasing pH, reaches a minimum, and then increases with further increa...