Dilatancy, Jamming, and the Physics of Granulation
- Event time: 1:00pm
- Event date: 28th February 2005
- Speaker: Mike Cates (Formerly School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Under some conditions, a dense colloidal suspension, although flowable at low shear rates, is converted into a paste-like assembly of granules, surrounded by air, at high shear rates. (This is the basis of 'high shear mixer granulation' as used in industry.) Central to the stability of these granules is the capillary force arising from the interfacial tension between the suspending solvent and the surrounding air. This force appears capable of maintaining the granule in a jammed solid state, under conditions where exactly the same amount of solvent and colloid could also exist as a flowable droplet. A schematic model of colloidal arrest under stress gives a wide range of possible flow curves depending on the colloidal interactions. Combining this model with ideas about capillarity I will speculate upon various jamming and granulation scenarios, and interpret these in relation to recent experiments by Mark Haw and others.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..