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Shear jamming and fragility in fractal suspensions under confinement
Sarika C K1, Sayantan Majumdar1, A K Sood2
1Soft Condensed Matter Group, Raman Research Institute, Bengaluru 560080, India. smajumdar@rri.res.in.
Soft Matter
|November 11, 2022
Summary
Fractal suspensions of carbon nanotubes exhibit shear jamming (SJ) at ultra-low concentrations, transitioning directly from flow to solid-like states without discontinuous shear-thickening (DST). This reveals the fragile nature of SJ and its dynamics.
Area of Science:
- Rheology and soft matter physics
- Materials science and nanotechnology
Background:
- Dense particulate suspensions exhibit discontinuous shear-thickening (DST) and shear jamming (SJ) under stress.
- Shear jamming in fractal suspensions remains unexplored, particularly at low concentrations.
Purpose of the Study:
- Investigate shear jamming in ultra-dilute fractal suspensions of multi-walled carbon nanotubes (MWCNT).
- Explore the transition dynamics from flowing to shear jammed states.
- Characterize the fragility and contact dynamics of the shear jammed state.
Main Methods:
- Rheology measurements
- In situ optical imaging
- Application of a generalized Wyart-Cates model
Main Results:
- Direct transition from flowing to shear jammed state observed in fractal suspensions at ultra-low volume fractions (ϕ ∼ 0.5%).
- Absence of a precursory discontinuous shear-thickening (DST) phase.
- Demonstration of the fragile nature and contact dynamics of the shear jammed state.
Conclusions:
- Fractal suspensions can exhibit shear jamming without prior DST at significantly lower concentrations than conventional suspensions.
- A generic phase diagram for fractal suspensions is proposed, encompassing SJ without DST.
- The study highlights novel flow behaviors in confined ultra-dilute fractal systems.
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