Drop coalescence in planar extensional flow and gravity

Jeelani, Shaik; Windhab, Erich J.

doi:10.1016/j.ces.2009.03.003

Cited by 10 publications

(5 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Investigating thin films of foams, Scheludko (1957), Scheludko and Exerowa (1959), and Scheludko et al (1965) revealed the fundamental aspects of disjoining pressure in drainage films with immobile interfaces covered with surfactants. Jeelani and Windhab (2009) were able to predict coalescence times and critical film thicknesses of several published experimental investigations based on the proposed drainage model of Jeelani and Hartland (1994).…”

Section: Drainage Modelsmentioning

confidence: 98%

Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches

Kamp

Villwock

Kraume

2016

Reviews in Chemical Engineering

125

106

View full text Add to dashboard Cite

AbstractThe coalescence phenomenon of drops in liquid/liquid systems is reviewed with particular focus on its technical relevance and application. Due to the complexity of coalescence, a comprehensive survey of the coalescence process and the numerous influencing factors is given. Subsequently, available experimental techniques with different levels of detail are summarized and compared. These techniques can be divided in simple settling tests for qualitative coalescence behavior investigations and gravity settler design, single-drop coalescence studies at flat interfaces as well as between droplets, and detailed film drainage analysis. To model the coalescence rate in liquid/liquid systems on a technical scale, the generic population balance framework is introduced. Additionally, different coalescence modeling approaches are reviewed with ascending level of detail from empirical correlations to comprehensive film drainage models and detailed computational fluid and particle dynamics.

show abstract

Section: Drainage Modelsmentioning

confidence: 98%

Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches

Kamp

Villwock

Kraume

2016

Reviews in Chemical Engineering

125

106

View full text Add to dashboard Cite

show abstract

“…Several physical phenomena including flow-induced conformational changes of macromolecules (Dunlap and Leal, 1987), shear-induced crystallization of polymers (Torza, 1975), or drop coalescence (Jeelani and Windhab, 2009) have been performed by using this flow device. However, any studies on proteins have, to our knowledge, not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Physical degradation of proteins in well‐defined fluid flows studied within a four‐roll apparatus

Simon

Krause

Weber

2011

Biotech & Bioengineering

View full text Add to dashboard Cite

In most applications of biotechnology and downstream processing proteins are exposed to fluid stresses in various flow configurations which often lead to the formation of unwanted protein aggregates. In this paper we present physical degradation experiments for proteins under well-defined flow conditions in a four-roll apparatus. The flow field was characterized numerically by computational fluid dynamics (CFD) and experimentally by particle image velocimetry (PIV). The local shear strain rate as well as the local shear and elongation rate was used to characterize the hydrodynamic stress environment acting on the proteins. Lysozyme was used as a model protein and subjected to well-defined fluid stresses in high and low stress environment. By using in situ turbidity measurements during stressing the aggregate formation was monitored directly in the fluid flow. An increase in absorbance at 350 nm was attributed to a higher content of visible particles (>1 µm). In addition to lysozyme, the formation of aggregates was confirmed for two larger proteins (bovine serum albumin and alcohol dehydrogenase). Thus, the presented experimental setup is a helpful tool to monitor flow-induced protein aggregation with high reproducibility. For instance, screening experiments for formulation development of biopharmaceuticals for fill and finish operations can be performed in the lab-scale in a short time-period if the stress distributions in the application are transferred and applied in the four-roll mill.

show abstract

“…In studies of multicomponent polymer blends of more than two phases, papers dedicated to this subject have shown that the morphology resulting from the competition between drops collision under flow followed by coalescence/encapsulation or drop breakup depends mainly on the interfacial and rheological properties. , The final droplet size distribution, under mixing, results from the balance between the present phenomena . Recently, the effect of compatibilization on the deformation and breakup of drops in stepwise increasing shear flow has been investigated…”

Section: Introductionmentioning

confidence: 99%

“…20,21 The final droplet size distribution, under mixing, results from the balance between the present phenomena. 22 Recently, the effect of compatibilization on the deformation and breakup of drops in stepwise increasing shear flow has been investigated. 23 Hobbs et al 24 first reported the encapsulation concept on the spontaneous development of the composite droplet morphology in immiscible systems.…”

Section: Introductionmentioning

confidence: 99%

2D Encapsulation in Multiphase Polymers: Role of Viscoelastic, Geometrical and Interfacial Properties

2011

View full text Add to dashboard Cite

The aim of the present work has been to gain a fundamental understanding of the mechanisms governing encapsulation in the multiphase systems as a blend or multilayer structures. The model systems chosen for this study are based on (i) Newtonian poly(dimethylsiloxane) polymers of varying molar masses and (ii) high molecular weight, viscoelastic, and compatible pair polymers of PVDF and PMMA. The same approach was applied to functionalized polymers to investigate the effect of physicochemical affinity on two pairs of asymmetrical reactive polymers based on PE-GMA (glycidyl methacrylate)/PVDF-g-MA (maleic anhydride) and a PE/PVDF as a reference. The linear viscoelastic and surface properties of the neat and bilayer model systems structures have been investigated. The optical obeservations of the encapsulation kinetic of two drops were recorded using a homemade device. Specific experiments were carried out to follow up the kinetic of encapsulation, and the results were rationalized as a function of the effect of the viscosity, elasticity ratios, drop geometry, the interfacial tension, and the physicochemical affinity. Throughout all the experiment, the mechanisms were purposed for each system and discussed based on the theories of molecular forces or Brownian motion governing diffusion and Ostwald ripening, in contrast to the theories of coalescence. The viscosity ratio coupled to the drop geometry of the material was found to be a key parameter and that it has to be linked to the interfacial tension and spreading parameters. Furthermore, the encapsulation appeared to be hindered by the interdiffusion process in the case of compatible pair system despite their elasticity and surface tension contrast. Finally, the encapsulation kinetic could be reduced or eliminated by the creation of a copolymer at the interface for a reactive system. The results obtained by the optical investigation of two drops corroborated the rheological data of the bilayer systems. Hence, the obtained results rendered it possible to decouple the influence of the viscoelastic parameters to flow, interfacial tension, thereby highlighting a number of macroscopic effects that were governed by the interdiffusion or reaction of macromolecular chains at the interface to give a better understanding of encapsulation phenomenon in multiphase systems.

show abstract

Drop coalescence in planar extensional flow and gravity

Cited by 10 publications

References 26 publications

Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches

Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches

Physical degradation of proteins in well‐defined fluid flows studied within a four‐roll apparatus

2D Encapsulation in Multiphase Polymers: Role of Viscoelastic, Geometrical and Interfacial Properties

Contact Info

Product

Resources

About