Complex viscosity of graphene suspensions

Haddad, Kais; Aumnate, Chuanchom; Saengow, Chaimongkol; Kanso, M. A.; Coombs, S. J.; Giacomin, A. Jeffrey

doi:10.1063/5.0063753

Cited by 12 publications

(3 citation statements)

References 14 publications

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“…To compare their 3D results to our 2D model, we need to translate the bending rigidity parameter from 3D to 2D. To do so, we use the relation B ¼ 2RD ¼ E 1 6 Rh 3 obtained assuming that the cross section of the sheet is a rectangle of width equal to the diameter 2R and height h. With this relation, S % 5 Â 10 À3 corresponds to _ c L ' 500, slightly larger than what we observe but of the same order of magnitude (for this calculation, we have assumed an incompressible material, for which 2 ( 1). A semi-analytical result for the buckling threshold of disks was derived by Lingard and Whitmore 44 to model the buckling of red blood cells in shear flows.…”

Section: Discussionmentioning

confidence: 99%

“…Applications of graphene and other two-dimensional (2D) materials suspended in shear liquids pose new scientific questions for the fluid dynamics and non-linear mechanics of thin structures. [1][2][3][4] Two-dimensional nanomaterials are sheet-like crystals of atomic thickness which often take the form of colloidal particles. In this form, they are most often processed in the liquid state (e.g., in inks, [5][6][7] coatings, 8,9 polymer nanocomposite processing 10,11 and in liquid-phase exfoliation 12,13 ).…”

Section: Introductionmentioning

confidence: 99%

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Simulation of interacting elastic sheets in shear flow: Insights into buckling, sliding, and reassembly of graphene nanosheets in sheared liquids

et al. 2022

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In liquid-based material processing, hydrodynamic forces are known to produce severe bending deformations of two-dimensional (2D) materials such as graphene. The non-linear rotational and deformation dynamics of these atomically thin sheets is extremely sensitive to hydrodynamic particle-particle interactions. To investigate this problem, we developed a computational model of the flow dynamics of elastic sheets suspended in a linear shear flow, solving the full fluid-solid coupling problem in the two-dimensional, slender-body, Stokes flow regime. Both single and pairs of sheets in close proximity are analyzed. Despite the model being two-dimensional, the critical non-dimensional shear rate yielding single-particle buckling is comparable in order of magnitude to that reported for fully three-dimensional, disk-like sheets. For pairs of interacting sheets, hydrodynamic interactions lead either to parallel sliding or bending, depending on the value of an elasto-viscous number based on particle length. For sufficiently low bending rigidity or large shear rates, large deformations of initially stacked sheets lead to sheet reattachment after separation, unlike for the rigid case. A peeling-like dynamics where lubrication provides a viscous bonding force is observed for sheet pairs when one of the two sheets is more rigid than the other. Practical implications for graphene processing and exfoliation are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of interacting elastic sheets in shear flow: Insights into buckling, sliding, and reassembly of graphene nanosheets in sheared liquids

et al. 2022

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“…26,27 It is well documented that improving exfoliation efficiency and quality depends on further analysis of solvent selection and cavitation behavior, which changes with the characteristic properties of liquids. [28][29][30] Previous research [25][26][27]31,32 provides the foundation to expect that cavitation dynamics and SW propagation may vary distinctly due to significantly different density, surface tension, viscosity, vapor pressure, and speed of sound in the studied liquids. The results of this work can be applied to a wider range of dual frequency sonoprocesses where different properties are required, such as emulsification, 33 sonochemical synthesis, 34,35 in clinical practice, 36 and most notably the exfoliation of 2D nanomaterials.…”

Section: Introductionmentioning

confidence: 99%

Dual frequency ultrasonic cavitation in various liquids: High-speed imaging and acoustic pressure measurements

et al. 2023

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Ultrasonic cavitation is used in various processes and applications, utilising powerful shock waves and high-speed liquid jets generated by the collapsing bubbles. Typically, a single frequency source is used to produce the desired effects. However, optimisation of the efficiency of ultrasound reactors is necessary to improve cavitation activity in specific applications such as for the exfoliation of two dimensional (2D) materials. This research takes the next step to investigate the effect of a dual frequency transducer system on the bubble dynamics, cavitation zone, pressure fields, acoustic spectra and induced shock waves for four liquids with a range of physical properties. Using ultra-high-speed imaging and synchronised acoustic pressure measurements, the effect of ultrasonic dual frequencies on bubble dynamics was investigated. The addition of a high frequency transducer (1174 kHz) showed that the bubble fragments and satellite bubbles induced from a low frequency transducer (24 kHz) were able to extend their lifecycle, increase spatial distribution, thus, extending the boundaries of the cavitation zone. Furthermore, this combination of ultrasonic frequencies generated higher acoustic pressures (up to 180%) and enhanced the characteristic shock wave peak, indicating more bubble collapses and the generation of additional shock waves. The dual frequency system also enlarged the cavitation cloud size under the sonotrode. These observations specifically delineated the enhancement of cavitation activity using a dual frequency system pivotal for optimisation of existing cavitation-based processing technologies.

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Complex viscosity of star-branched macromolecules from analytical general rigid bead-rod theory

et al. 2021

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Complex viscosity of graphene suspensions

Cited by 12 publications

References 14 publications

Simulation of interacting elastic sheets in shear flow: Insights into buckling, sliding, and reassembly of graphene nanosheets in sheared liquids

Simulation of interacting elastic sheets in shear flow: Insights into buckling, sliding, and reassembly of graphene nanosheets in sheared liquids

Dual frequency ultrasonic cavitation in various liquids: High-speed imaging and acoustic pressure measurements

Complex viscosity of star-branched macromolecules from analytical general rigid bead-rod theory

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