Interfacial dilational rheology by oscillating bubble/drop methods

Ravera, Francesca; Loglio, G.; Kovalchuk, V. I.

doi:10.1016/j.cocis.2010.04.001

Cited by 201 publications

(167 citation statements)

References 80 publications

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“…Dilatational measuring techniques are used to investigate the equilibrium and dynamic properties of simple and complex interfacial layers composed of low-molecular--weight surfactants (LMWS), proteins and polymers (24). Furthermore, these techniques can be used to monitor surfactant concentration, competitive adsorption and the magnitude of interactions at the interface.…”

Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

“…6, is widely used for the determination of mechanical properties at gas-liquid and liquid-liquid interfaces, and is applicable to a great variety of liquids, from organic to molten metals, for which very small amounts of sample are required. Major drawbacks of the method include the requisite density difference between the two involved fluids and the requirement that the inter- face must be close to mechanical equilibrium when it is analysed (the interface must be investigated at low frequencies) (24). The drop/bubble shape is defined by a combination of surface tension and gravitational force: surface forces prefer spherical drops/bubbles, and gravity attempts to elongate or compress the drop/bubble.…”

Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

“…In the last twenty years, oscillating drop and bubble techniques have been developed and are now the most commonly used techniques for surface dilatational rheology (3). These techniques can be used to study rheological properties at both liquid-liquid and gas-liquid interfaces and are based on either the shape measurement of a drop/ bubble or on the measurement of the capillary pressure inside a drop/bubble (24).…”

Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

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Interfacial rheology: An overview of measuring techniques and its role in dispersions and electrospinning

Pelipenko¹,

Kristl²,

Rošic³

et al. 2012

Acta Pharmaceutica

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Colloidal disperse systems represent the increasing number of modern delivery systems whose primary characteristic, a large interfacial area, causes thermodynamic instability. Therefore, the foremost challenge in dispersion design is the reduction of interface instability and an understanding of the behaviour of interfaces. Interfacial rheology is one of the most powerful tools for observing occurrences at the interphase. As previously mentioned, the stability of such systems is provided by the formation of a stable interfacial layer of surfactants around each dispersible particle. The stability of these systems can be improved by using more than one surfactant, but it must be kept in mind that different surfactants can have varying mechanisms of stabilisation, some of which can be mutually incompatible. Surfactant selection is therefore crucial and must be based on physicochemical properties, stability of the interfacial film, mobility of the molecules in the interfacial film, HLB, film formation kinetics, compatibility and interactions between molecules on the surface, CMC, etc. Interfacial rheological properties have yet to be thoroughly explored. Only recently, methods have been introduced that provide sufficient sensitivity to reliably determine viscoelastic interfacial properties. In general, interfacial rheology describes the relationship between the deformation of an interface and the stresses exerted on it.Due to the variety in deformations of the interfacial layer (shear and expansions or compressions), the field of interfacial rheology is divided into the subcategories of shear and dilatational rheology. While shear rheology is primarily linked to the long-term stability of dispersions, dilatational rheology provides information regarding short-term stability. Interfacial rheological characteristics become relevant in systems with large interfacial areas, such as emulsions and foams, and in processes that lead to a large increase in the interfacial area, such as electrospinning of nanofibers.

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Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

Section: Dilatational Measuring Techniquesmentioning

confidence: 99%

See 1 more Smart Citation

Interfacial rheology: An overview of measuring techniques and its role in dispersions and electrospinning

Pelipenko¹,

Kristl²,

Rošic³

et al. 2012

Acta Pharmaceutica

View full text Add to dashboard Cite

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“…The droplet area and interfacial tension changes were recorded over time to obtain the viscous and elastic moduli. 19,46,47 The droplet volume change was set to 10% during the oscillation, with the oscillation frequency of 0.1 Hz. Each reported dilatational elasticity consisted of 10 oscillations with a 10 s delay between each subsequent measurement.…”

Section: Dilatational Elasticity Measurementsmentioning

confidence: 99%

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

et al. 2017

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Atomic force microscopy (AFM) is frequently used to elucidate complex interactions in emulsion systems. However, comparing results obtained with "model" planar surfaces to curved emulsion interfaces often proves unreliable, since droplet curvature can affect adsorption and arrangement of surface-active species, while droplet deformation affects the net interaction force.In the current study, AFM was utilized to study the interactions between a colloidal probe and water droplet. Force magnitude and water droplet deformation were measured in asphaltene and bitumen solutions of different concentrations at various droplet aging times. Interfacial stiffening and an increase in particle-droplet adhesion force were observed upon droplet aging in bitumen solution. As reported in our previous study (Kuznicki, N. P.; Harbottle, D.; Masliyah, J.; Xu, Z. Dynamic Interactions between a Silica Sphere and Deformable Interfaces in Organic SolventsStudied by Atomic Force Microscopy. Langmuir 2016, 32 (38), 9797−9806), a viscoelasticity parameter should be included in the high force Stokes-Reynolds-Young-Laplace (SRYL) equations to account for the interfacial stiffening and non-Laplacian response of the water droplet at longer aging times. However, following the addition of a biodegradable demulsifier, ethyl cellulose (EC), an immediate reduction in both the particle-droplet adhesion force and the rigidity of the water droplet occurred. Following EC addition, the interface reverted back to a 2 Laplacian response and droplet deformation was once again accurately predicted by the classical SRYL model. These changes in both droplet deformation and particle-droplet adhesion, tracked by AFM, imply a rapid asphaltene/bitumen film displacement by EC molecules. The colloidal probe technique provides a convenient way to quantify forces at deformable oil/water interfaces and characterize the in-situ effectiveness of competing surface active species.

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“…Rayleigh's work was extended by Lamb [2], who included the influence of viscosity of the drop liquid and obtained the oscillation frequency and the rate of decay of the oscillations in the limits of very high and very low drop viscosity. The idea to measure material properties of liquids from damped drop shape oscillations has brought about the oscillating drop method [3,4]. To date, the existing literature discusses the measurement of material parameters, such as the dynamic viscosity of the liquid and its surface tension against the ambient medium, predominantly for Newtonian liquids [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Measurement of polymeric time scales from linear drop oscillations

Plohl¹,

Brenn²

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The oscillating drop method allows material properties of liquids to be measured from damped drop oscillations. The literature discusses, e.g., the measurement of the liquid dynamic viscosity and the surface tension against the ambient medium, predominantly for Newtonian liquids. We use this method for measuring pairs of material properties of polymeric liquids. Pairs of properties may be measured, since the quantity measured is a complex frequency with a real and an imaginary part. For the measurements, individual drops are levitated in air by an ultrasonic levitator and imaged with a high-speed camera. Amplitude modulation of the ultrasound drives shape oscillations of the levitated drop. When the modulation is switched off, with the levitating force maintained, the drop performs free oscillations which are damped due to the liquid viscosity. The data acquired from the images recorded are the angular frequency and the damping rate which are used as an input into the characteristic equation of the oscillating drop. Our measurements intend to yield either two viscoelastic time scales with the zero-shear viscosity known, or one time scale and the zero-shear viscosity, with the other time scale known. The two time scales are the stress relaxation and the deformation retardation times. The latter is difficult to get for polymer solutions. The present contribution presents results from a large set of measurements of the deformation retardation time. Liquids studied are aqueous solutions of poly(acryl-amides) at varying concentration. The corresponding values of the zero-shear viscosity agree well with the values from shear rheometry. Values of the deformation retardation time differ substantially from the values commonly used in viscoelastic flow simulations. Furthermore, the measured values disagree with the predictions from the viscous-elastic stress splitting approach in linear viscoelasticity. With our study we will provide a consistent set of material properties for the Oldroyd-B model in linear viscoelasticity. This will be important for material modelling in viscoelastic spray simulations.

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Interfacial dilational rheology by oscillating bubble/drop methods

Cited by 201 publications

References 80 publications

Interfacial rheology: An overview of measuring techniques and its role in dispersions and electrospinning

Interfacial rheology: An overview of measuring techniques and its role in dispersions and electrospinning

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

Measurement of polymeric time scales from linear drop oscillations

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