2009 Volume 95 Issue 12 Pages 807-812
Viscosity of multi-phases fluids, suspensions of spherical polyethylene beads dispersed in silicone oils, has been measured by rotating cylinder method. Results were obtained as functions of the volume fraction and the average particle size of dispersed beads, the viscosity of silicone oil and shear rate at the surface of rotating spindle. In addition, the rheological characterization of the multi-phase fluids was examined from the relationship between the shear rate and the shear stress calculated on the basis of experimental conditions and the viscosity data.
The apparent viscosities of the multi-phases fluids were found to increase exponentially with increasing the volume fraction of polyethylene beads. Moreover, in the case of the volume fraction of beads were higher than 0.3, the viscosity of these fluids decreased with increasing the shear rate. The relationships between shear stress and shear rate indicated that the highly concentrated fluids with the beads (the volume fraction of the beads were higher than 0.3) behaved as non-Newtonian fluids that were categorized as Bingham fluid.