Global strain field mapping of a particle-laden interface using digital image correlation

Vora, Sahil R.; Bognet, Brice; Patanwala, Huseini S.; Young, Christopher; Chang, Seunghyuk; Daux, V.; Anson, W. K.

doi:10.1016/j.jcis.2017.08.082

Cited by 16 publications

(8 citation statements)

References 22 publications

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“…The average flow field created by the moving barriers is not purely dilatational. Therefore, the dynamic surface tension measured by the Wilhelmy-plate technique in conventional Langmuir troughs contains shear as well as dilatational components. − For the samples studied here (as will be discussed in the following paragraph), the surface dynamic properties in shear are negligible against those in dilatation; thus, the surface stress signal effectively reflects only the dilatational component.…”

Section: Methodsmentioning

confidence: 98%

Relaxation Behavior and Nonlinear Surface Rheology of PEO–PPO–PEO Triblock Copolymers at the Air–Water Interface

et al. 2019

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Surface dilatational viscoelasticity of adsorbed layers of pluronics triblock copolymers at the air–water interface was measured using the oscillating barrier technique. The effect of molecular architecture and concentration on surface viscoelasticity was explored for two different types of pluronics with different degrees of hydrophobicity, Pluronic F-108 (M w ≈ 14 600 g/mol) and Pluronic P-123 (M w ≈ 5800 g/mol), the former exhibiting a larger hydrophilic to hydrophobic block length ratio. Frequency sweeps in the linear regime suggested that interfacial films of F-108 have higher surface limiting elasticity and larger in-plane and out-of-plane relaxation times at the same bulk concentration (the former possibly related to in-plane microstructure rearrangements, the latter to surface/bulk diffusion). Increasing the bulk concentration of pluronics from 1 to 100 μM led to a decrease in both in- and out-of-plane relaxation times. Large amplitude oscillatory dilatation (LAOD) tests were performed to capture nonlinear behavior of these interfacial films by means of elastic and viscous Lissajous plots. Nonlinearities in elastic responses were quantified through calculation of the strain-stiffening indices in extension S E and compression S C. Both pluronics exhibited strain softening in extension. In compression, P-123 showed strain-hardening and F-108 displayed a relatively linear response. Apparent strain hardening in extension was observed for the P-123 adsorbed film, at high strain, at a bulk concentration of 100 μM. However, at these strains, the response was dominated by the viscous contribution and calculation of strain rate-thickening factors in extension and compression showed that the overall response was strain rate-thinning in extension and strain rate-thickening in compression.

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Section: Methodsmentioning

confidence: 98%

Relaxation Behavior and Nonlinear Surface Rheology of PEO–PPO–PEO Triblock Copolymers at the Air–Water Interface

et al. 2019

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“…By comparing the results pertaining to the rectangular trough (black, purple, and dark blue curves), we see that the parallel-oriented plate presents a change in slope at much higher Π values than the one oriented perpendicularly with respect to the barriers. This is because the deformation field has both shear and compressional components, and thus, different plate orientations pick up different stresses, ,,, implying that the layer at the air/water interface has a significant shear modulus, i.e., it is displaying a solid-like behavior. The inflection point at high surface pressure corresponds to a point where transparency of the surface layer is reduced due to the formation of structures, namely, dark stripes that can be seen by the naked eye and that are parallel to the barriers in the case of the rectangular trough.…”

Section: Resultsmentioning

confidence: 99%

“…Compression experiments are carried out in rectangular liquid–liquid Langmuir troughs (360 × 55 mm) from KSV NIMA (Biolin Scientific), as depicted in the first image of Figure . A uniaxial compression profile occurs if a slip condition at the trough’s side walls is satisfied; if this is not the case, a complex mixed deformation profile takes place, with compressional and shear components. , For stepwise compressions, a liquid–liquid trough with dimensions of 784 × 75 mm was also used due to its high maximum compression ratio. Both setups consist of a PTFE trough with two motor-controlled Delrin barriers, a sensitive electromagnetic balance (resolution, 0.1 μN/m) coupled to a Wilhelmy plate, using a fluid bath for temperature control.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, these measurements can be used in a regime where interfacial tension dominates over mechanical stresses but are not valid when such extra mechanical stresses become important. − A careful analysis and validity check of interfacial tension measurements and small-step deformation of an aqueous pendant drop immersed in an asphaltene solution were recently done by Rodríguez-Hakim et al, where it was shown that for such soluble systems, at short times and for quasi-static deformations, the Y–L equation remains valid. Second, as both thermodynamic and dilatation rheology contributions are isotropic, it is not straightforward to decouple them. ,, Also, the compression in the rectangular trough constitutes a complex deformation with the details of the deformation depending on the ratio between shear and compressional properties. − Finally, both shear and dilatational experiments are typically carried out using an asphaltene-soluble organic (aromatic) phase, such as toluene or xylene, or partially soluble, as is the case of studies using heptol, a combination of heptane and toluene, or even diluted crude oils and bitumen. In this way, results are reported in terms of bulk solution concentrations and it can be difficult to assess the interfacial coverage under these conditions.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the Interfacial Activity of Insoluble Asphaltene Layers: Interfacial Rheology versus Interfacial Tension

Alicke

Simon²,

Sjöblom³

et al. 2020

Langmuir

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Asphaltenes have been suggested to play an important role in the remarkable stability of some water-in-crude oil emulsions, although the precise mechanisms by which they act are not yet fully understood. Being one of the more polar fractions in crude oils, asphaltenes are surface active and strongly adsorb at the oil/water interface, and as the interface becomes densely packed, solid-like mechanical properties emerge, which influence many typical interfacial experiments. The present work focuses on purposefully measuring the rheology in the limit of an insoluble, spread Langmuir monolayer in the absence of adsorption/desorption phenomena. Moreover, the changes in surface tension are deconvoluted from the purely mechanical contribution to the surface stress by experiments with precise interfacial kinematics. Compression “isotherms” are combined with the measurement of both shear and dilatational rheological properties to evaluate the relative contributions of mechanical versus thermodynamic aspects, i.e., to evaluate the “interfacial rheological” versus the standard interfacial activity. The experimental results suggest that asphaltene nanoaggregates are not very efficient in lowering interfacial tension but rather impart significant mechanical stresses. Interestingly, physical aging effects are not observed in the spread layers, contrary to results for adsorbed layers. By further studying asphaltene fractions of different polarity, we investigate whether mere packing effects or strong interactions determine the mechanical response of the dense asphaltene systems as either soft glassy or gel-like responses have been reported. The compressional and rheological data reflect the dense packing, and the behavior is captured well by the soft glassy rheology model, but a more complicated multilayer structure may develop as coverage is increased. Potential implications of the experimental observations on these model and insoluble interfaces for water-in-crude oil emulsion stability are briefly discussed.

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“…In the latest years, image correlation has been widely used in a broad spectrum of fields, such as geothecnics [ 1 ], structural health monitoring [ 2 ], particle velocimetry [ 3 ], material characterization [ 4 ], or medicine [ 5 ], among others. In most of these applications there is not a clear target to follow, so the surface texture is used instead.…”

Section: Introductionmentioning

confidence: 99%

Parametric Evaluation of Errors Using Isolated Dots for Movement Measurement by Image Cross-Correlation

Mas

2018

Sensors

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Digital Image Correlation (DIC) is a common tool for assessing the movement of objects in a scene. Among others, one of the most popular techniques consists of tracking a dotted texture imitating speckle patterns. In this work, we analyzed the individual dots that form this pattern in order to propose an optimum size, shape, and dynamic range that allows minimizing the tracking error. Tracking was accomplished by using normalized cross-correlation with peak interpolation in order to obtain subpixel accuracy. For the models here used, we show that dot radii of 30–40 px with 150 gray levels are enough to obtain an accurate subpixel tracking resolution. Also, we show that 0.002 px is the performance limit of this technique, being this limit in accordance with the experimentally achievable subpixel limit.

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Global strain field mapping of a particle-laden interface using digital image correlation

Cited by 16 publications

References 22 publications

Relaxation Behavior and Nonlinear Surface Rheology of PEO–PPO–PEO Triblock Copolymers at the Air–Water Interface

Relaxation Behavior and Nonlinear Surface Rheology of PEO–PPO–PEO Triblock Copolymers at the Air–Water Interface

Assessing the Interfacial Activity of Insoluble Asphaltene Layers: Interfacial Rheology versus Interfacial Tension

Parametric Evaluation of Errors Using Isolated Dots for Movement Measurement by Image Cross-Correlation

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