Dynamic hysteresis in the rheology of complex fluids

Puisto, Antti; Mohtaschemi, Mikael; Alava, Mikko J.; Illa, Xavier

doi:10.1103/physreve.91.042314

Cited by 25 publications

(18 citation statements)

References 34 publications

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“…Our prediction of a monotonic decrease in the hysteresis loop areas with increasing δt in a simple yield stress fluid is in contrast with the earlier theoretical work Puisto et al 66 . We have argued that the non-monotonicity suggested in that earlier study stems from their having considered sweep times fast enough to be in the physically undesirable regime in which the downsweep and upsweep flow curves fail to meet at the highest strain rates, which was excluded from the experiments.…”

Section: Discussioncontrasting

confidence: 99%

“…13(b,d), as seen experimentally in panel (c) of the same figure. However, there is a clear separation in the location of the peak in A σ (nδt) compared with that for A v (nδt) in the theoretical results. Such a separation was also noted in the previous theoretical work of Puisto et al 66 for a simple yield stress fluid, although we suggest that the peak reported in that work should be treated with caution for the reasons discussed above.…”

Section: Comparison With Experiments and Other Theoretical Worksupporting

confidence: 85%

“…Alongside the experimental literature just described, theoretical attempts to model rheological hysteresis have been relatively limited in comparison. Many studies 45,50,[61][62][63][64][65][66] have considered so called 'fluidity models', or 'structural kinetics theories'. These typically pose a simple scalar constitutive equation for the time evolution of the shear stress σ, coupled to an equation describing the time evolution of an underlying property λ of the fluid, which may characterise the state of its microstructure or degree of dynamical fluidity.…”

mentioning

confidence: 99%

“…An important exception can be found in the work of Ref. 66 , which studied a fluidity model of a simple yield stress fluid, coupled to the Navier-Stokes equation to allow any heterogeneity in the flow profile to be computed. This successfully predicted rheological hysteresis and the time-dependent shear-banding associated with it.…”

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confidence: 99%

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Understanding rheological hysteresis in soft glassy materials

et al. 2017

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Motivated by recent experimental studies of rheological hysteresis in soft glassy materials, we study numerically strain rate sweeps in simple yield stress fluids and viscosity bifurcating yield stress fluids. Our simulations of downward followed by upward strain rate sweeps, performed within fluidity models and the soft glassy rheology model, successfully capture the experimentally observed monotonic decrease of the area of the rheological hysteresis loop with sweep time in simple yield stress fluids, and the bell shaped dependence of hysteresis loop area on sweep time in viscosity bifurcating fluids. We provide arguments explaining these two different functional forms in terms of differing tendencies of simple and viscosity bifurcating fluids to form shear-bands during the sweeps, and show that the banding behaviour captured by our simulations indeed agrees with that reported experimentally. We also discuss the difference in hysteresis behaviour between inelastic and viscoelastic fluids. Our simulations qualitatively agree with the experimental data discussed here for four different soft glassy materials.Many soft materials, including emulsions, 1 foams, 2 colloids, 3,4 microgels 5 and star polymers 6 display exotic rheological behaviour intermediate between that of liquids and solids.7,8 At rest, or under low imposed strains, they behave as weak elastic solids and often also show ageing behaviour, in which a sample becomes progressively more solid-like as a function of the time since it was prepared.9-11 In contrast, for imposed stresses larger than a threshold yield stress σ y , they show more liquid-like response, although the resulting flow might be spatially homogeneous or heterogeneous, 12 steady or strongly time dependent, 13 depending on the nature of the interactions between the constituent particles, 1,13-15 the shear history [16][17][18] and even the boundary conditions. 19,20 Such phenomena have been attributed to the generic presence in these 'soft glassy materials' (SGMs) 21,22 of structural disorder and metastability.Understanding the rheology of soft glasses remains the focus of considerable ongoing debate.23,24 Many practical applications require the determination of the flow curve σ(γ), which links the shear stress σ to the shear rateγ under conditions of a steady shear flow. Experimentally, the measurement of this curve usually involves sweeping the shear rate (or shear stress) up or down over some prescribed interval, with some prescribed temporal duration for the sweep. While the aim is to measure the steady-state flow curve, in practice a time-dependent response is often seen. In any fluid with a fixed intrinsic relaxation timescale, the departure from steady-state can be quantified by comparing that relaxation timescale to the time of the sweep. In a glassy material, however, the typical relaxation timescale is a complicated function of the imposed flow history. In practice, therefore, the usual strategy is to compare flow curve measurements obtained in a sequence comprising an upward fo...

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Section: Discussioncontrasting

confidence: 99%

Section: Comparison With Experiments and Other Theoretical Worksupporting

confidence: 85%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Understanding rheological hysteresis in soft glassy materials

et al. 2017

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“…intermediate (longterm) stages of strong and weak diffusion localization throughout the process. Example of this is the characterization of the long-term reversibility and hysteresis of externally triggered [61][62] and self-oscillating materials. 63 …”

Section: Discussionmentioning

confidence: 99%

In situ characterization of structural dynamics in swelling hydrogels

et al. 2016

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Characterizing the structural morphology and the local viscoelastic properties of soft complex systems raises significant challenges. Here we introduce a dynamic light scattering method capable of in situ, continuous monitoring of structural changes in evolving systems such as swelling gels. We show that the inherently non-stationary dynamics of embedded probes can be followed using partially coherent radiation, which effectively isolates only single scattering contributions even during the dramatic changes in the scattering regime. Using a simple and robust experimental setup, we demonstrate the ability to continuously monitor the structural dynamics of chitosan hydrogels formed by the Ag(+) ion-triggered gelation during their long-term swelling process. We demonstrate that both the local viscoelastic properties of the suspending medium and an effective cage size experienced by diffusing probe particles loaded into the hydrogel can be recovered and used to describe the structural dynamics of hydrogels with different levels of cross-linking. This characterization capability is critical for defining and controlling the hydrogel performance in different biomedical applications.

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