Quantifying the destructuring of a thixotropic colloidal suspension using falling ball viscometry

The settling dynamics of falling spheres inside a Laponite suspension is studied. colloidal synthetic clay that shows physical aging in aqueous due to the spontaneous evolution inter-particle electrostatic interactions. In our experiments, millimeter-sized steel balls are dropped suspensions different ages (i.e., time elapsed since sample preparation). motion captured using high-speed camera and velocities their centroids estimated from images. Interestingly, we observe larger diameters fail achieve terminal velocity over entire duration experiment. We propose mathematical model accounts for rapid structural changes (expected be induced by ball) whose scales much slower than fall ball. For range ball sizes ages, correctly predicts time-dependence velocity. Furthermore, fits allow us estimate rates destructuring thixotropic passage