A double wall-ring geometry for interfacial shear rheometry

Vandebril, Steven; Franck, Aly; Fuller, Gerald G.; Moldenaers, Paula; Vermant, Jan

doi:10.1007/s00397-009-0407-3

Cited by 283 publications

(291 citation statements)

References 35 publications

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“…To correct for any torque contributions arising from the induced sub-phase flow, we corrected all of our measurements for non-linearity using the MATLAB script described by Vandebril et al 21 (kindly provided by Jan Vermant, K.U. Leuven,Belgium), and confirmed that this correction did not make any appreciable difference to the measured data for the range of interfacial properties that characterize the BSA solutions studied here.…”

Section: Methodssupporting

confidence: 56%

“…In a recent paper 20 , we demonstrated that this apparent bulk yield stress and the associated shear thinning rheological response in fact arises from the presence of a viscoelastic layer formed due to protein adsorption at the air-water interface. We used the recently-developed interfacial double wall ring (DWR) 21 fix- ture mounted on a stress-controlled rheometer to carry out a series of interfacial rheological measurements in steady and oscillatory shear. We augmented these measurements with bulk and interface-free microfluidic rheometry data to highlight the strong influence that the interfacial layer has on bulk rheology.…”

Section: Introductionmentioning

confidence: 99%

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Interfacial viscoelasticity, yielding and creep ringing of globular protein–surfactant mixtures

2011

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Protein-surfactant mixtures arise in many industrial and biological systems, and indeed, blood itself is a mixture of serum albumins along with various other surface-active components. Bovine serum albumin (BSA) solutions, and globular proteins in general, exhibit an apparent yield stress in bulk rheological measurements at surprisingly low concentrations. By contrasting interfacial rheological measurements with corresponding interface-free data obtained using a microfluidic rheometer, we show that the apparent yield stress exhibited by these solutions arises from the presence of a viscoelastic layer formed due to the adsorption of protein molecules at the air-water interface. The coupling between instrument inertia and surface elasticity in a controlled stress device also results in a distinctive damped oscillatory strain response during creep experiments known as"creep ringing". We show that this response can be exploited to extract the interfacial storage and loss moduli of the protein interface. The interfacial creep response at small strains can be described by a simple second order system, such as the linear Jeffreys model, however the interfacial response rapidly becomes nonlinear beyond strains of order 1%. We use the two complementary techniques of interfacial rheometry and microfluidic rheometry to examine the systematic changes in the surface and bulk material functions for mixtures of a common non-ionic surfactant, Polysorbate 80, and BSA. It is observed that the nonlinear viscoelastic properties of the interface are significantly suppressed by the presence of even a relatively small amount of surfactant (c surf > 10 −3 wt.%).

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Section: Methodssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Interfacial viscoelasticity, yielding and creep ringing of globular protein–surfactant mixtures

2011

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“…Initially, the drops are held apart for up to 6 hr at a separation distance of 0.55 mm, t = 0 s. After a desired aging period, the drop fixed on the capillary was lowered towards the second drop, with the displacement and rate of approach controlled by a computer activated speaker diaphragm. In the current study, the total capillary displacement was set to 670 m providing an apparent drop-drop overlap of 120 m, thus ensuring that the drops were in intimate Interfacial rheology using Double Wall Ring (DWR) geometry -an AR-G2 controlled stress rheometer (TA Instruments, Canada) with double wall ring (DWR) geometry 24 was used to measure the viscoelasticity and shear yield stress of asphaltene-stabilized films. The DWR geometry is used in combination with a circular channel Delrin ® trough.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Problematic Stabilizing Films in Petroleum Emulsions: Shear Rheological Response of Viscoelastic Asphaltene Films and the Effect on Drop Coalescence

et al. 2014

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Adsorption of asphaltenes at the water-oil interface contributes to the stability of petroleum emulsions by forming a networked film that can hinder drop-drop coalescence. The interfacial microstructure can either be liquid-like or solid-like, depending on: i) initial bulk concentration of asphaltenes, ii) interfacial aging time, and iii) solvent aromaticity. Two techniques: interfacial shear rheology and integrated thin film drainage apparatus provided equivalent interface aging conditions, enabling direct correlation of the interfacial rheology and droplet stability. The shear rheological properties of the asphaltene film were found to be critical to the stability of contacting droplets. With a viscous dominant interfacial microstructure, the coalescence time for two drops in intimate contact was rapid, on the order of seconds. However, as the elastic contribution develops and the film microstructure begins to be dominated by elasticity, the two drops in contact do not coalescence. Such step-change transition in coalescence is thought to be related to the high shear yield stress (~10 4 Pa), which is a function of the film shear yield point and the film thickness (as measured by quartz crystal microbalance), and the increased elastic stiffness of the film that prevents mobility and rupture of the asphaltene film which when in a solid-like state provides an energy barrier for the droplets to coalescence.

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“…Details about this measuring geometry can be found in. 27 The viscoelastic properties were recorded at a frequency of 0.7 Hz and a deformation amplitude of 1%, which did not exceed the linear viscoelastic regime of any sample solution. From these measurements we have determined the surface elastic modulus G 0 i .…”

Section: Solution Preparation and Measurementsmentioning

confidence: 99%

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Lexis

Willenbacher

2014

Soft Matter

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We have determined bulk rheology of b-lactoglobulin (BLG) foams and surface viscoelasticity of corresponding protein solutions by varying pH as well as type, valency and concentration of the added salt in a wide range. Foam rheology was characterized by the storage modulus G 0 , the apparent yield stress s y , and the critical strain g c,foam defining the cessation of the linear viscoelastic response. These quantities were determined at gas volume fractions f between 82% and 96%. Surface viscoelasticity was characterized in shear and dilation, corresponding shear and dilational moduli G 0 i , E 0 as well as the critical stress s c,surface and strain g c,surface marking the onset of non-linear response in oscillatory surface shear experiments were determined at fixed frequency. Beyond the widely accepted assumption that G 0 and s y are solely determined by the Laplace pressure within the droplets and the gas volume fraction we have found that both quantities strongly depend on corresponding interfacial properties. G 0 increases linearly with G 0 i and even stronger with E 0 , s y varies proportional to s c,surface and g c,foam scales linearly with g c,surface . Furthermore, deviations from these simple scaling laws with significantly higher reduced G 0 and s y values are observed only for foams at pH 5 and when a trivalent salt was added. Then also the dependence of these quantities on f is unusually weak and we attribute these findings to protein aggregation and structure formation across the lamellae than the dominating bulk rheology.

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A double wall-ring geometry for interfacial shear rheometry

Cited by 283 publications

References 35 publications

Interfacial viscoelasticity, yielding and creep ringing of globular protein–surfactant mixtures

Interfacial viscoelasticity, yielding and creep ringing of globular protein–surfactant mixtures

Problematic Stabilizing Films in Petroleum Emulsions: Shear Rheological Response of Viscoelastic Asphaltene Films and the Effect on Drop Coalescence

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

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