Structures, stresses, and fluctuations in the delayed failure of colloidal gels

@article{Lindstrm2012StructuresSA,
  title={Structures, stresses, and fluctuations in the delayed failure of colloidal gels},
  author={Stefan B. Lindstr{\"o}m and Thomas E. Kodger and Joris Sprakel and David A. Weitz},
  journal={Soft Matter},
  year={2012},
  volume={8},
  pages={3657-3664}
}
Sample-spanning networks of aggregated colloidal particles have a finite stiffness and deform elastically when subjected to a small shear stress. After some period of creep, these gels ultimately suffer catastrophic failure. This delayed yielding is governed by the association and dissociation dynamics of interparticle bonds and the strand structure of the gel. We derive a model which connects the kinetics of the colloids to the erosion of the strand structure and ultimately to macroscopic… 

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References

SHOWING 1-10 OF 42 REFERENCES

Stress enhancement in the delayed yielding of colloidal gels.

It is shown that the time delay for this yielding decreases in two distinct exponential regimes with applied stress, universal and found for a variety of colloidal gel systems.

Delayed flow in thermo-reversible colloidal gels

In this study we present a systematic investigation of the highly nonlinear creep behavior of thermo-reversible gels composed of octadecyl coated silica particles suspended in decalin. These

Heterogeneous yielding dynamics in a colloidal gel

Attractive colloidal gels display a solid-to-fluid transition as shear stresses above the yield stress are applied. This shear-induced transition is involved in virtually any application of colloidal

Arrested fluid-fluid phase separation in depletion systems: Implications of the characteristic length on gel formation and rheology

We investigate the structural, dynamical, and rheological properties of colloid-polymer mixtures in a volume fraction range of ϕ=0.15–0.35. Our systems are density-matched, residual charges are

Spontaneous coarsening of a colloidal network driven by self-generated mechanical stress

Colloidal suspensions can be regarded as an ideal model system for such key daily materials as emulsions, protein solutions, foods, and inks. When colloidal particles strongly attract each other,

Towards rationalising collapse times for the delayed sedimentation of weakly-aggregated colloidal gels

By delayed sedimentation is meant the rapid collapse of a colloidal gel following a period of either little or no sedimentation. The delay or collapse time can range from seconds to many months,

Dynamic strength of molecular adhesion bonds.

The role of solid friction in the sedimentation of strongly attractive colloidal gels

We study experimentally and theoretically the sedimentation of gels made of strongly aggregated colloidal particles, focusing on the long-time behaviour, when mechanical equilibrium is asymptotically

Flow-Induced Anisotropy and Reversible Aggregation in Two-Dimensional Suspensions

The time evolution of the flow-induced changes in structure of two-dimensional suspensions have been studied by means of video microscopy. The interparticle forces were tailored to produce a

Gelation of particles with short-range attraction

Experiments are reported showing that gelation of spherical particles with isotropic, short-range attractions is initiated by spinodal decomposition; this thermodynamic instability triggers the formation of density fluctuations, leading to spanning clusters that dynamically arrest to create a gel.