8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.101Consolidation and yielding behaviour of an aqueousnanoscale titanium dioxide systemAlastair Mailer 11 University of Edinburgh, Room 2509, JCMB, Kings Buildings EH9 3JZ, Edinburgh,United KingdomNanometer-sized colloidal titanium dioxide is an industrially important material used in manyproducts, from suncreams to photovoltaic cells. With both a high refractive index and a highdensity, this system demonstrates aggregation and sedimentation behaviour arising from the competitionbetween strong van der Waals attraction, electrostatic repulsion and gravitational stress.I will be presenting results on the characterisation of a titanium dioxide system at low volumefraction (0. 01% to 10%) and variable surface charge adjusted by addition of hydrochloric acid(0mV to -40mV) dispersed using an ultrasonic probe. Three regimes are present: isolated clustersat low volume fraction and surface charge, gravitational consolidation at intermediate values andfree standing gels at higher volume fractions. Insights into these regimes will be presented fromanalysis of dynamic light scattering, macroscopic timelapse photography and rheology data foreach regime respectively. The results of the analysis will be compared to the poroelastic/yieldingmodel of colloidal gel collapse.101