FORMATION OF A HIGHLY ORDERED COLLOIDAL MICROSTRUCTURE UPON FLOW CESSATION FROM HIGH-SHEAR RATES

A model suspension of charged colloidal spheres exhibits anomalous mod ulus relaxations upon flow cessation from the shear-thickened state. S mall angle neutron scattering (SANS) measurements indicate the develop ment of a metastable crystalline state upon flow cessation from a diso rdered, shear-thickened state. The metastable state consists of a rand om stacking of tightly packed hcp planes of particles lying in the she ar velocity-vorticity plane. These measurements suggest that the appar ently disordered shear-thickened state may contain a high degree of la tent order not apparent in the SANS measurements during flow.