Factors affecting the rheology and processability of highly filled suspensions

Suspensions filled with rigid particles at volume-loading levels that approach their maximum packing fraction are widely encountered, especially in the energetics, ceramics, pharmaceutical, magnetics, composites, food, and personal care industries. Highly filled suspensions, regardless of industrial application, exhibit a number of common rheological and processability traits, including viscoplasticity and wall slip, that necessitate special rheometers and appropriate characterization and numerical simulation methods. Furthermore, various factors, including the dispersion and distribution of the particles and their agglomerates, the entrainment of air, the filtration-based migration of the binder phase, and the shear-induced migration of particles, play important roles and must be considered in the design and optimization of manufacturing operations for processing of highly filled suspensions.