title: Shear banding and flow-concentration coupling in colloidal glasses.
abstract: We report experiments on hard-sphere colloidal glasses that show a type of shear banding hitherto unobserved in soft glasses. We present a scenario that relates this to an instability due to shear-concentration coupling, a mechanism previously thought unimportant in these materials. Below a characteristic shear rate γ(c) we observe increasingly nonlinear and localized velocity profiles. We attribute this to very slight concentration gradients in the unstable flow regime. A simple model accounts for both the observed increase of γ(c) with concentration, and the fluctuations in the flow.
authors.affiliation: SUPA, School of Physics & Astronomy, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Besseling
authors.forename: L
authors.initials: L
authors.lastname: Isa
authors.forename: P
authors.initials: P
authors.lastname: Ballesta
authors.forename: G
authors.initials: G
authors.lastname: Petekidis
authors.forename: M E
authors.initials: ME
authors.lastname: Cates
authors.forename: W C K
authors.initials: WC
authors.lastname: Poon