Viscoelastic and shear-thinning effects of aqueous exopolymer solution on disk and sphere settling

Mrokowska, Magdalena M.; Krztoń‐Maziopa, A.

doi:10.1038/s41598-019-44233-z

Cited by 44 publications

(16 citation statements)

References 57 publications

(124 reference statements)

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“…Polymer melts and aqueous solutions also exhibit a non-Newtonian behavior. Those mixtures mostly display shear thinning, − but, even if less common, a shear thickening effect can be encountered. , Bokias et al reported that in most cases, shear thickening is not very pronounced and appears only at rather low shear rates. As a general trend, the overall rheological behavior of polymer aqueous solutions is driven by both the polymer concentration and microstructure, , since they determine the nature and the ability of forming inter- and intrachain junctions (usually reversible) for polymer macromolecules in aqueous media. , In such a way, flexible-backbone (block) copolymers with amphiphilic properties were synthesized over the past decades to have water-soluble entities. , Usually, water-soluble polymers are modified to contain a small number of hydrophobic groups .…”

Section: Introductionmentioning

confidence: 99%

Neat and Aqueous Polyelectrolytes under a Steady-Shear Flow

et al. 2021

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Materials enabling impact-energy absorption of high-velocity projectiles are of great interest for applications like aerospace. In such a frame, shear thickening fluids were found very useful. Here, we investigated nanorheological properties of neat and aqueous polyelectrolytes of low molecular weights containing poly([2-(methacryloyloxy) ethyl] trimethyl ammonium) as polycations and poly(acrylamide-co-acrylic acid) as polyanions. Results were compared with pure water. We employed nonequilibrium molecular dynamics with the SLLOD algorithm to compute the viscosity at various shear rates. Systems containing polyelectrolytes exhibit shear thickening. The analysis of molecular configurations revealed a strong disruption of the ionic structure and more clusters with smaller sizes on increasing the shear rate. Potential energies showed that shear thickening originates from an increase in intramolecular and van der Waals interactions resulting from the increasing difficultly of polyelectrolyte-based systems to relax at high shear rates. Our method and findings underscore the importance of accounting for the molecular scale in the design of materials absorbing the impact energy efficiently.

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Section: Introductionmentioning

confidence: 99%

Neat and Aqueous Polyelectrolytes under a Steady-Shear Flow

et al. 2021

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“…Image pre-processing, processing and analysis were carried out using ImageJ and MATLAB® as in the previous studies 25 , 51 . In each raw grayscale image, a particle was detected using thresholding.…”

Section: Methodsmentioning

confidence: 99%

Influence of pycnocline on settling behaviour of non-spherical particle and wake evolution

Mrokowska

2020

Sci Rep

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Settling of non-spherical particles in a stratified fluid exhibits complex dynamics in a low-to-moderate inertia regime. Although this process is involved in a wide variety of phenomena in natural fluid systems, its fundamental mechanisms are still unexplored. Understanding of particle settling in microscale is particularly important to explain challenging problems associated with ecological and biogeochemical processes in the ocean due to the delayed settling of particulate matter at pycnoclines. Here, I explore interactions between disk-shaped particles and a stratified fluid with a density transition. By laboratory experiments, I demonstrate that the settling dynamics of the disk crossing a density transition are tightly coupled with the wake structure evolution, and I observe for the first time in a two-layer ambient configuration a bell-shaped structure that forms on a jet after the wake has detached from the particle. Furthermore, I identify hydrodynamic conditions for the variations of settling velocity and particle orientation instabilities. These findings shed light on particle settling mechanisms necessary to explain dynamics of marine particles such as plankton, faecal pellets, and microplastics and may improve the estimation methods of sedimentation processes in various areas of earth sciences and engineering.

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“…A negative wake has also been observed for solid spheres settling in viscoelastic fluids [51][52][53]. A large amount of research has been done on the "negative wake" of solid balls and discs compared with the experimental research done for bubbles, owing to the instability of the bubble surface [51,54,55]. ese studies show that the so-called "negative wake" could be observed in the wake of solid spheres over a wide range of Deborah numbers.…”

Section: The Negative Wake Phenomenonmentioning

confidence: 96%

Review of Single Bubble Motion Characteristics Rising in Viscoelastic Liquids

Wang

2021

International Journal of Chemical Engineering

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The emphasis of this review is to discuss three peculiar phenomena of bubbles rising in viscoelastic fluids, namely, the formation of a cusp, negative wake, and velocity jump discontinuity, and to highlight the possible future directions of the subject. The mechanism and influencing factors of these three peculiar phenomena have been discussed in detail in this review. The evolution of the bubble shape is mainly related to the viscoelasticity of the fluid. However, the mechanisms of the two-dimensional cusp, tip-streaming, “blade-edge” tip, “fish-bone” tip, and the phenomenon of the tail breaking into two different threads, in some special viscoelastic fluids, are not understood clearly. The origin of the negative wake behind the bubbles rising in a viscoelastic fluid can be attributed to the synergistic effect of the liquid-phase viscoelasticity, and the bubbles are large enough; thus, leading to a very long relaxation time taken by the viscoelastic stresses. For the phenomenon of bubble velocity jump discontinuity, viscoelasticity is the most critical factor, and the cusp of the bubbles and the surface modifications play only ancillary roles. It has also been observed that a negative wake does not cause velocity jump discontinuity.

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Viscoelastic and shear-thinning effects of aqueous exopolymer solution on disk and sphere settling

Cited by 44 publications

References 57 publications

Neat and Aqueous Polyelectrolytes under a Steady-Shear Flow

Neat and Aqueous Polyelectrolytes under a Steady-Shear Flow

Influence of pycnocline on settling behaviour of non-spherical particle and wake evolution

Review of Single Bubble Motion Characteristics Rising in Viscoelastic Liquids

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