Discontinuous Jamming Transitions in Soft Materials

TL;DR

This paper reviews experimental evidence for discontinuous jamming transitions in soft materials, highlighting the coexistence of flowing and solid-like states with abrupt changes in strain rate.

Contribution

It provides a comprehensive review of experimental findings on discontinuous jamming transitions, emphasizing the role of shear localization and shear banding.

Findings

Evidence for abrupt strain rate changes in soft materials.

Coexistence of flowing and solid-like states during jamming.

Discontinuous transitions often linked to shear banding phenomena.

Abstract

Many systems in nature exhibit transitions between fluid-like states and solid-like states, or "jamming transitions". There is a strong theoretical foundation for understanding equilibrium phase transitions that involve solidification, or jamming. Other jamming transitions, such as the glass transition, are less well-understood. The jamming phase diagram has been proposed to unify the description of equilibrium phase transitions, the glass transitions, and other non-equilibrium jamming transitions. As with equilibrium phase transitions, which can either be first order (discontinuous in a relevant order parameter) or second order (continuous), one would expect that generalized jamming transitions can be continuous or discontinuous. In studies of flow in complex fluids, there is a wide range of evidence for discontinuous transitions, mostly in the context of shear localization, or shear banding. In this paper, I review the experimental evidence for discontinuous transitions. I focus on systems in which there is a discontinuity in the rate of strain between two, coexisting states: one in which the material is flowing and the other in which it is solid-like.