Relationship between rheology and morphology of model blends in steady shear flow

Vinckier, Inge; Moldenaers, Paula; Mewis, Jan

doi:10.1122/1.550800

Cited by 257 publications

(163 citation statements)

References 15 publications

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“…As elasticity effects are negligible, the components behave as Newtonian fluids under the measurement conditions. 39 The viscosities m and d of PIB and PDMS, respectively, are 103.8 and 103.7 Pa s at 23.7°C, resulting in a viscosity ratio close to 1 at room temperature. The interfacial tension of the PDMS/PIB system is …”

Section: Methodsmentioning

confidence: 99%

Microconfined equiviscous droplet deformation: Comparison of experimental and numerical results

et al. 2008

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The dynamics of confined droplets in shear flow is investigated using computational and experimental techniques for a viscosity ratio of unity. Numerical calculations, using a boundary integral method ͑BIM͒ in which the Green's functions are modified to include wall effects, are quantitatively compared with the results of confined droplet experiments performed in a counter-rotating parallel plate device. For a viscosity ratio of unity, it is experimentally seen that confinement induces a sigmoidal droplet shape during shear flow. Contrary to other models, this modified BIM model is capable of predicting the correct droplet shape during startup and steady state. The model also predicts an increase in droplet deformation and more orientation toward the flow direction with increasing degree of confinement, which is all experimentally confirmed. For highly confined droplets, oscillatory behavior is seen upon startup of flow, characterized by an overshoot in droplet length followed by droplet retraction. Finally, in the case of a viscosity ratio of unity, a minor effect of confinement on the critical capillary number is observed both numerically and experimentally.

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Section: Methodsmentioning

confidence: 99%

Microconfined equiviscous droplet deformation: Comparison of experimental and numerical results

et al. 2008

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“…During the manufacturing process, an in-dividual droplet at the microscopic level deforms to various shapes, breaks up or interacts with neighboring droplets, and experiences a complicated flow history [2]. Accurate prediction of how the morphology evolves in the mixer is thus essential in the development of polymer blends with specific material properties.…”

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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“…In many cases mutual solubility is considered to be negligible for practical purposes. [4][5][6][10][11][12] This seems reasonable since the polymers consist of long molecules, and mixing of those molecules is thermodynamically unfavorable. 13 Moreover, polymers possess a high ͑macroscopic͒ viscosity ͓typically from O͑1-10 3 ͒Pa s͔ and therefore mutual diffusion if present, is expected to be slow ͑the mutual diffusion coefficient is of the order of 10 −13 cm 2 / s and smaller 14 ͒.…”

Section: Introductionmentioning

confidence: 99%

Transient interfacial tension and dilatational rheology of diffuse polymer-polymer interfaces

Peters

Zdravkov

Meijer

2005

The Journal of Chemical Physics

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We demonstrate the influence of molecular weight and molecular weight asymmetry across an interface on the transient behavior of the interfacial tension. The interfacial tension was measured as a function of time for a range of polymer combinations with a broad range of interfacial properties using a pendant/sessile drop apparatus. The results show that neglecting mutual solubility, assumed to be a reasonable approximation in many cases, very often does not sustain. Instead, a diffuse interface layer develops in time with a corresponding transient interfacial tension. Depending on the specific combination of polymers, the transient interfacial tension is found to increase or decrease with time. The results are interpreted in terms of a recently proposed model ͓Shi et al., Macromolecules 37, 1591 ͑2004͔͒, giving relative characteristic diffusion time scales in terms of molecular weight, molecular weight distribution, and viscosities. However, the time scales obtained from this theoretical approach do not give a conclusive trend. Using oscillatory dilatational interfacial experiments the viscoelastic behavior of these diffusive interfaces is demonstrated. The time evolution of the interfacial tension and the dilatational elasticity show the same trend as predicted by the theory of diffuse interfaces, supporting the idea that the polymer combinations under consideration indeed form diffuse interfaces. The dilatational elasticity and the dilatational viscosity show a frequency dependency that is described qualitatively by a simple Fickian diffusion model and quantitatively by a Maxwell model. The characteristic diffusion times provided by the latter show that the systems with thick interfaces ͑tens of microseconds and more͒ can be considered as slower diffusive systems compared to the systems with thinner interfaces ͑a few micrometers in thickness and less͒ can be considered as fast diffusive systems.

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Relationship between rheology and morphology of model blends in steady shear flow

Cited by 257 publications

References 15 publications

Microconfined equiviscous droplet deformation: Comparison of experimental and numerical results

Microconfined equiviscous droplet deformation: Comparison of experimental and numerical results

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

Transient interfacial tension and dilatational rheology of diffuse polymer-polymer interfaces

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