Viscosity models for concentrated suspensions of solid core‐porous shell particles

Abstract

New models are developed for the low-shear viscosity of concentrated suspensions of solid coreporous shell particles taking into consideration the effects of the thickness and permeability of shell surrounding the solid core of the core-shell particles. The relative viscosity of suspension depends on factors such as: relative thickness of the porous shell, size of the composite (solid core-porous shell) particles, permeability of the shell, and volume fraction of the core particles.For given relative thickness of porous layer and size of the composite particles, the relative viscosity of suspension decreases substantially with the i ncrease in the permeability of the porous layer at a fixed volume fraction of core particles. Upon shrinking of the solid core, the relative viscosity of suspension exhibits a large increase provided that the size of the composite particles, the permeability of the porous shell, and the volume fraction of core particles are all kept constant. The proposed models are evaluated using data available on low-shear viscosity of concentrated suspensions of three different types of particles: porous particles, solid core -hairy shell particles, and hard spheres.

Effect of Particle Specific Surface Area on the Rheology of Non-Brownian Silica Suspensions

“…The non-Newtonian rheology of the faceted particles was attributed to the higher contribution of the contact viscosity to the total suspension viscosity value at increasing particle volume fractions, since particle contacts were favoured in the case of irregularly shaped particles [ 9 ]. Particle porosity has also been observed to significantly increase suspension viscosity through an increase in the effective particle volume fraction as compared with the apparent one, as the pores absorb part of the solvent [ 14 , 15 ].…”