NIST Technicalendar Single Item Display: Announcement Item ID: 114352Erik0.660982427019

SEMINAR 04/06/07 THE EFFECT OF PARTICLE SHAPE ON THE SHEAR-INDUCED JAMMING OF DENSE SUSPENSIONS
Ryan J. Larsen, School of Engineering and Applied Sciences, Harvard University - Discontinuous shear thickening, or shear jamming, occurs when dense colloidal suspensions undergo a shear-induced transition from fluid-like properties to solid-like properties. Because jamming is associated with geometrical confinement of the particles, it is reasonable to expect particle shape to have an effect on the jamming of suspensions. To test this dependence, we synthesize uniform polystyrene particles of dumbbell and triangle shape and compare their jamming behavior to that of similar spheres. We show that the non-spherical particles display more dramatic viscosity increases during jamming, they persist in the jammed state for longer periods of time, and they are more dilatant. Our results suggest that non-spherical particles form more rigid structures because they have rotational degrees of freedom not available to spherical particles.

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