Effects of Starting Powder Characteristics on Bulk Assembly of Titania

Seven nanoscale titanias synthesized from a sulfate process were investigated for rheological characterization. Alteration of synthesis parameters had resulted in variation of the powder surface area and soluble sulfate level from powder to powder. The powder differences were further corroborated in stress-controlled rheometry where the viscoelastic yield stress of a suspension was seen to vary strongly with processing history. Capillary and torque rheometry further showed the dependence of processing history on steady-state extrusion pressure and steady-state mixing torque. The powders were washed to determine whether sulfate equilibration through washing could be used to circumvent the synthesis parameter differences.