Slip effects in viscometric flows of highly filled suspensions

In this report, the behavior of a highly filled (60% by volume) suspension in capillary and parallel disk rotational flows was studied, with emphasis on migration and wall slip. Information on pressure as well as drag flows of such highly concentrated suspensions with highly viscous matrices had been lacking. This study is part of a larger study which includes the simulation and experimental studies of the continuous processing of highly filled suspensions in co-rotating twin screw extruders. It is shown the slip velocity at the wall values were determined over three decades of shear stress values. The flow of the suspension studied in this report exhibits shear thinning behavior at low shear stress values measured by parallel disk viscometry. However, at higher shear stress values, the shear viscosity increases with the shear stress, exhibiting rheological dilatancy.