In first approximation, settling may be easily described by Stokes law taking into account dynamic viscosity η and in case of high solids concentration, a suitable hindrance function. In centrifugal field centrifugal acceleration has to be used instead of gravitational acceleration.
Settling studies based solely on visual inspection have been increasingly replaced by instrumental methods since decades. Accelerated stability testing using centrifuges is applied in many formulation and research labs as a standard protocol. This assumes a good correlation with results obtained by visual observation as well as with results obtained at earth gravity, however, related investigations on real world complex dispersions are rare. In this work settling of aqueous suspensions of technical grade titania samples was evaluated in viscous but Newtonian liquids (aqueous solutions of sucrose or glycerol) in the regime of high particle concentration (up to 28 % v/v) as well as in the regime of low particle concentration (< 0.1 % v/v). Results obtained by visual observation at gravity and by instrumental measurement were compared using STEP-Technology both at gravity (LRPSA/LR-X-Ray) and in centrifugal field (LS)...
Session: L1 - Particle and Slurry Characterization
Day: 22 October 2019
Time: 13:00 - 14:15 h