Experimental Study on the Breakup of Model Viscoelastic Drops in Uniform Shear Flow

Varanasi, Padma Prabodh; Ryan, Michael E.; Stroeve, Pieter

doi:10.1021/ie00031a028

Cited by 55 publications

(30 citation statements)

References 19 publications

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“…For PLA-j/PA11-LV and PLA/PA11-LV, the interfacial tension (G 12 ) at processing temperature is determined by Palierne model [34], using the SEM images analysis (Section 4.3), shear oscillation rheometry (Section 4.2) and relaxation times (Section 4.2) measurements:…”

Section: Interfacial Tension Assessmentmentioning

confidence: 99%

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

et al. 2018

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Bio-based poly(L-lactide)/poly(amide-11) blends (PLA/PA11, 80/20 w/w) and poly(L-lactide)/poly(amide-6) blends (PLA/PA6, 80/20 w/w) are processed by twin-screw extrusion followed by injection-moulding and key rheological parameters controlling their morphologie are investigated. The same work is done using the same PLA modified by a multi-step reactive extrusion route with an epoxy-based chain extender to obtain modified poly(lactide)/poly(amide-11) (PLA-j/PA11 80/20 w/w) blends. The morphologies of the extruded materials and of the injection moulded parts are characterized by SEM and their formation is deeply discussed via rheological investigation to highlight the contribution of viscosity, elasticity and interfacial tension. The existence of a critical shear rate related to the transition from nodular to fibrillar morphology is highlighted and the results are in good agreement with the condition of fibrillation Ca/Ca (crit) $ 4. Interestingly, with the exception of PLA/PA6 specimens, all blends obviously display uniform thin-thread fibrillar morphologies after injection-moulding. Compared with pure PLA, a drastic increase of the ductility was observed in the blends exhibiting a fiberlike structure without meanwhile sacrificing the stiffness. This study confirms that, through the appropriate choice of blend components (viscosity and elasticity ratio, flow conditions, interfacial tensions) the in situ fibrillation concept provides access, at a reasonable cost, to new materials with improved thermomechanical performances, without sacrificing weight and ability to be recycled.

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Section: Interfacial Tension Assessmentmentioning

confidence: 99%

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

et al. 2018

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“…More recently, confirming these results, a decrease of the interfacial tension with time was found for several Newtonian systems. 17 A fast decrease, followed by an increase of the interfacial tension was reported 18 ͑limited, small volume͒ to the continuous phase ͑unlimited, large volume͒. The increase of the interfacial tension was found to be due to the transfer of the surfactant into the continuous phase resulting in a depletion in the drop and in the interfacial area.…”

Section: Introductionmentioning

confidence: 96%

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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“…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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Experimental Study on the Breakup of Model Viscoelastic Drops in Uniform Shear Flow

Cited by 55 publications

References 19 publications

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

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

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

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