The rheology of concentrated suspensions of deformable particles

The rheology of slightly deformable particles, in particular their dilatant behaviour, has been investigated using waxy maize starch as a ‘model’ suspension. Suspensions of such large particles present considerable experimental problems in rheological terms in that they exhibit phenomena such as wall slip and sedimentation. These are discussed in some detail, along with the methodologies developed to overcome them. Comparisons of the results with hard sphere data in the literature indicate that whilst the deformability of the starch granules does not play a significant role in the high shear limiting viscosity, the dilatant transition does appear to be strongly affected.