Pairwise frictional profile between particles determines discontinuous shear thickening transition in non-colloidal suspensions
Pairwise frictional profile between particles determines discontinuous shear thickening transition in non-colloidal suspensions
- Event time: 11:30am until 12:30pm
- Event date: 1st June 2018
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Event details
The process by which sheared suspensions go through a dramatic change in viscosity is
known as discontinuous shear thickening. Although well-characterized on the macroscale,
the microscopic mechanisms at play in this transition are still poorly understood. Here,
by developing new experimental procedures based on quartz-tuning fork atomic force
microscopy, we measure the pairwise frictional profile between approaching pairs of polyvinyl
chloride and cornstarch particles in solvent. We report a clear transition from a low-friction
regime, where pairs of particles support a finite normal load, while interacting purely
hydrodynamically, to a high-friction regime characterized by hard repulsive contact between
the particles and sliding friction. Critically, we show that the normal stress needed to enter
the frictional regime at nanoscale matches the critical stress at which shear thickening occurs
for macroscopic suspensions. Our experiments bridge nano and macroscales and provide
long needed demonstration of the role of frictional forces in discontinuous shear thickening.
Event resources
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