Rheology of concentrated suspensions of spheres. II. Suspensions agglomerated by an immiscible second liquid

Small amounts of a second immiscible liquid, water, were introduced into suspensions of glass beads (untreated or surface treated with dimethyldichlorosilane) in liquid polybutadiene. Water formed liquid bridges between the particles and caused the suspensions containing untreated beads to agglomerate. These large agglomerates changed the flow behavior from Newtonian to pseudoplastic. The extrapolated Bingham yield stress went through a maximum as the amount of water increased. Surfactants first decrease the pseudoplastic behavior and then, at higher concentrations, surfactants cause the suspensions to become Newtonian in behavior. A theory was developed in an attempt to explain the experimental results. The theory predicts pseudoplastic flow behavior for agglomerated suspensions, but the quantitative correlation between theory and experiment is not satisfactory.