An experimental study is proposed to explore the dynamics of shear thickening and microstructural changes in suspensions of uniform particle. The effects on the onset and magnitude of shear thickening of the continuous phase viscosity, particle size, particle density and volumn fraction will be explored. Both repulsive and attractive interaction potentials will be studied using model suspensions where the pair potential can be characterized from low volume fraction studies. Microstructures will be studied with small angle neutron scattering (SANS) and optical scattering techniques. Evidence of shear rate or stress induced structural phase transitions and the existence of metastable viscosities will be sought. The kinetics of such transitions and their effects on rheological behavior will be investigated. The structural changes occurring in suspensions with increasing shear rate and resulting increases in viscosity (shear thickening) are important in a wide range of technologies involving processing of dense suspensions.
