The yield stress tensor

Thompson, Roney L.; Sica, Luiz Umberto Rodrigues; Mendes, Paulo R. de Souza

doi:10.1016/j.jnnfm.2018.09.003

Cited by 50 publications

(24 citation statements)

References 35 publications

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“…In our experiments, 600 s was used for the creep step, which is much longer compared to coalescence timescales in emulsions that is typically on the order of a few seconds. Also, it is important to note that the shear yield stress is one contribution to the total yield stress tensor, as has been recently discussed for bulk rheology as well. , The dilatational/compressional yield stress is more difficult to measure, even for bulk rheology, but is reported to be several times higher than the shear counterpart.…”

Section: Resultsmentioning

confidence: 92%

“…Also, it is important to note that the shear yield stress is one contribution to the total yield stress tensor, as has been recently discussed for bulk rheology as well. 89,90 The dilatational/compressional yield stress is more difficult to measure, even for bulk rheology, but is reported to be several times higher than the shear counterpart.…”

Section: ■ Materials and Methodsmentioning

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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Section: Resultsmentioning

confidence: 92%

Section: ■ Materials and Methodsmentioning

confidence: 99%

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

Alicke

Simon²,

Sjöblom³

et al. 2020

Langmuir

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show abstract

“…Yield stress for 3D stress states should depend on the geometry of deformation. Indeed, yielding was observed for extension [ 69 ], and it convinces that the effect of yielding is the 3D phenomenon, and the value of the yield stress should be presented as a tensor [ 70 , 71 ]. The theoretical consideration assumed that the critical point for the solid-to-liquid transition in the 3D stress state is determined by the von Mises criterion quite like the rupture of solid material.…”

Section: Yielding—structure Breakdown Leading To Solid-to-liquid Tran...mentioning

confidence: 99%

The Role of Structure in Polymer Rheology: Review

Куличихин

Malkin

2022

Polymers

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The review is devoted to the analysis of the current state of understanding relationships among the deformation-induced structure transformations, observed rheological properties, and the occurrence of non-linear effects for polymer liquids (melts, solutions, and composites). Three levels of non-linearity are the base for consideration. The first one concerns changes in the relaxation spectra of viscoelastic liquids, which are responsible for weak non-linear phenomena. The second one refers to the strong non-linearity corresponding to such changes in the structure of a medium that leads to the emergence of a new relaxation state of a matter. Finally, the third one describes the deformation-induced changes in the phase state and/or the occurring of bifurcations and instability in flow and reflects the thermodynamic non-linear behavior. From a structure point of view, a common cause of the non-linear effects is the orientation of macromolecules and changes in intermolecular interaction, while a dominant factor in describing fluid dynamics of polymer liquids is their elasticity. The modern understanding of thixotropic effects, yielding viscoplastic materials, deformation-induced phase transition, and the experimental observations, demonstrating direct correlations between the structure and rheology of polymer liquids, are the main objects for discussion. All these topics are reviewed and discussed mainly on the basis of the latest five-year publications.

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“…In the present study, the normal yield stress [25] and the yield stress tensor [26] were approximated by measuring only the static shear yield stress ( ). We then assumed that the measured was close to normal yield stress.…”

Section: Rheological Characterisation Of Silicone Elastomer Formulationsmentioning

confidence: 99%

“…The sentence has been changed to: "In the present study, the normal yield stress [25] and the yield stress tensor [26] were approximated by measuring only the static shear yield stress ( )". We split this sentence in two: "The other two designs were evaluation objects, namely an ear (Fig.…”

Section: Comments To the Authormentioning

confidence: 99%

FingerMap: a new approach to predict soft material 3D objects printability

2020

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Soft material 3D printing through Liquid Deposition Modelling (LDM) is a challenging manufacturing process where yield stress control is mandatory. Indeed, the higher the yield stress value, the more complex the 3D printed structure can be. In a bid to go one step further, this report proposes a new approach enabling the prediction of soft material 3D printability as a function of the material's properties and shape. The prediction consists in numerical simulation to anticipate, in silico, the collapse of a voxelized 3D design, called FingerMap. To do so, a calibration of the program using three silicone formulations (with increasing yield stress value) was first performed to define a printability domain according to mass/surface ratio, overhang angle and the zposition of each voxel. Then, two anatomical 3D models (ear and aortic valve) were used to demonstrate the capacity of the tool to predict printability. Good correlations between theoretical and experimental results were obtained. The proposed in silico simulation tool was then proven to be useful for LDM, even if some limitations were identified, particularly in the case of materials exhibiting complex rheological behaviours such as time-dependent rheological properties.

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The yield stress tensor

Cited by 50 publications

References 35 publications

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

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

The Role of Structure in Polymer Rheology: Review

FingerMap: a new approach to predict soft material 3D objects printability

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