A study on polymer blending microrheology: Part 1

Elmendorp, J. J.; Maalcke, R. J.

doi:10.1002/pen.760251608

Cited by 127 publications

(67 citation statements)

References 21 publications

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“…Thus, the opposing trends observed in experiments must be due to finite viscoelastic effects, on which the perturbation solution can shed little light. Maffettone & Greco (2004) and Yu et al (2005) predicted reduced drop deformation, in agreement with the experiment of Guido et al (2003) and contradicting those of Elmendorp & Maalcke (1985) and Mighri et al (1998). Because of the phenomenological nature of these models, however, they do not provide any insight into the underlying physics.…”

Section: Introductionsupporting

confidence: 65%

“…If the drop phase is viscoelastic, there is again consensus that it inhibits deformation. This effect has been observed experimentally by Elmendorp & Maalcke (1985), Mighri, Carreau & Ajji (1998) and Lerdwijitjarud, Sirivat & Larson (2004), and predicted by Pillapakkam & Singh (2001) and Maffettone & Greco (2004). When the suspending fluid is viscoelastic, however, there is contradiction among the experiments.…”

Section: Introductionmentioning

confidence: 74%

“…When the suspending fluid is viscoelastic, however, there is contradiction among the experiments. Elmendorp & Maalcke (1985), using shear-thinning polymer solutions as the matrix, observed that increasing the normal stress in the matrix increases the deformation of a Newtonian drop. Mighri et al (1998) reached the same conclusion by using Boger fluids.…”

Section: Introductionmentioning

confidence: 99%

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Viscoelastic effects on drop deformation in steady shear

et al. 2005

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This paper applies a diffuse-interface model to simulate the deformation of single drops in steady shear flows when one of the components is viscoelastic, represented by an Oldroyd-B model. In Newtonian fluids, drop deformation is dominated by the competition between interfacial tension and viscous forces due to flow. A fundamental question is how viscoelasticity in the drop or matrix phase influences drop deformation in shear. To answer this question, one has to deal with the dual complexity of nonNewtonian rheology and interfacial dynamics. Recently, we developed a diffuse-interface formulation that incorporates complex rheology and interfacial dynamics in a unified framework. Using a two-dimensional spectral implementation, our simulations show that, in agreement with observations, a viscoelastic drop deforms less than a comparable Newtonian drop. When the matrix is viscoelastic, however, the drop deformation is suppressed when the Deborah number De is small, but increases with De for larger De. This non-monotonic dependence on matrix viscoelasticity resolves an apparent contradiction in previous experiments. By analysing the flow and stress fields near the interface, we trace the effects to the normal stress in the viscoelastic phase and its modification of the flow field. These results, along with prior experimental observations, form a coherent picture of viscoelastic effects on steady-state drop deformation in shear.

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Section: Introductionsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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Viscoelastic effects on drop deformation in steady shear

et al. 2005

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“…It is generally accepted that viscoelasticity stabilizes unconfined droplets against break-up [16][17][18][19][20][21][22][23][24][25]. It has also been theoretically predicted that viscoelastic effects show up in the droplet deformation in terms of two dimensionless parameters: the Deborah number, De = N 1 R 2σ 1 Ca 2 , where N 1 is the first normal stress difference generated in simple shear flow [26], and the ratio N 2 /N 1 between the second and first normal stresses difference [27].…”

Section: Introductionmentioning

confidence: 99%

Deformation and breakup of viscoelastic droplets in confined shear flow

Gupta

Sbragaglia

2014

Phys. Rev. E

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The deformation and break-up of Newtonian/viscoelastic droplets are studied in confined shear flow. Our numerical approach is based on a combination of lattice-Boltzmann models (LBM) and finite difference schemes, the former used to model two immiscible fluids with variable viscous ratio, and the latter used to model the polymer dynamics. The kinetics of the polymers is introduced using constitutive equations for viscoelastic fluids with finitely extensible non-linear elastic dumbbells with Peterlin's closure (FENE-P).We quantify the droplet response by changing the polymer relaxation time τ P , the maximum extensibility L of the polymers, and the degree of confinement, i.e. the ratio of the droplet diameter to wall separation. In unconfined shear flow, the effects of droplet viscoelasticity on the critical Capillary number Ca cr for breakup are moderate in all cases studied. However, in confined conditions a different behaviour is observed: the critical Capillary number of a viscoelastic droplet increases or decreases, depending on the maximum elongation of the polymers, the latter affecting the extensional viscosity of the polymeric solution. Force balance is monitored in the numerical simulations to validate the physical picture.

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“…Droplet breakup in blends with at least one viscoelastic component is studied in the experimental investigations of [22,23,24,25,26], which conclude that matrix and droplet viscoelasticity both inhibit droplet breakup. However, the majority of these studies include other hydrodynamic effects, nonhomogeneities in the applied flow field, shear-thinning behavior, or differences in the viscosity ratio among the various blend systems.…”

Section: Introductionmentioning

confidence: 99%

Influence of viscoelasticity on drop deformation and orientation in shear flow. Part 2: Dynamics

Verhulst

Cardinaels

Moldenaers

et al. 2009

Journal of Non-Newtonian Fluid Mechanics

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An experimental study of drop dynamics under shear is conducted for five fluid pairs: a reference Newtonian system, two systems with a viscoelastic drop in a Newtonian matrix, one with a Newtonian drop in a viscoelastic matrix, all at drop to matrix viscosity ratio λ = 1.5, and a separate case at λ = 0.75. The viscoelastic liquids are either a Boger fluid or a shear-thinning viscoelastic fluid satisfying an Ellis model. Deborah numbers in the range 1 to 2 and a range of capillary numbers from low to above breakup conditions are addressed. The results focus on three aspects: relaxation after cessation of shear, a new viscoelastic drop breakup scenario, and the effect of shear flow history on drop breakup. Numerical simulations with the 3D volume-of-fluid PROST method complement the experimental results.

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A study on polymer blending microrheology: Part 1

Cited by 127 publications

References 21 publications

Viscoelastic effects on drop deformation in steady shear

Viscoelastic effects on drop deformation in steady shear

Deformation and breakup of viscoelastic droplets in confined shear flow

Influence of viscoelasticity on drop deformation and orientation in shear flow. Part 2: Dynamics

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