The application of models for high solids content suspensions to pastes

Pastes are a combination of two phases: a solid phase raw material carried by a fluid phase composed of solvent, binder, and additives. Capillary rheometry of the fluid phase followed by capillary rheometry of a paste composition permits calculation of the relative paste bulk shear stress under most circumstances. Non-linear optimization is then used to determine the intrinsic viscosity, [ η], and maximum solids content, φ max, that best satisfy the chosen high solids content suspension model equation. Three criteria were developed that a candidate paste model equation must meet: it must model the experimental data with low error, it must be relatively insensitive to changes in [ η] and φ max, and it must arrive at sensible values for [ η] and φ max. In this investigation, the Mooney, Chong, and Dougherty-Krieger equations were tested. The Dougherty–Krieger equation best met the candidate paste model criteria and was used effectively to model paste properties.