Effect of roughness on the rheology of concentrated non-Brownian suspensions: A numerical study

More, Rishabh V.; Ardekani, Arezoo M.

doi:10.1122/1.5097794

Cited by 30 publications

(25 citation statements)

References 81 publications

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“…In order to provide a synthetic presentation of the large number of results shown in Fig. 7 and to be able to compare quantitatively the behaviors observed for the three types of suspensions, we will follow the approach of several authors that consists in considering that the jamming fraction,φ m is dependent on the stress magnitude 13,[20][21][22]32,35,41 . The variation of viscosity with particle volume fraction and shear stress is depicted using a modified Maron-Pierce law 81 :…”

Section: Resultsmentioning

confidence: 99%

“…A last possible cause of shear-thinning recently pointed out, is the decrease of the interparticle friction coefficient when the stress increases. For some years now, experimental evidence was produced to show that solid contacts do exist in sheared NBS 14,15 and several numerical studies showed that these contacts, especially frictional contacts, have a significant impact on the rheology (viscosity values [16][17][18] , non Newtonian behaviors [19][20][21][22] , normal stress differences 23 , shear-induced diffusion 24 . .…”

Section: Introductionmentioning

confidence: 99%

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Impact of particle stiffness on shear-thinning of non-Brownian suspensions

Gilbert

Valette

Lemaire

2021

Journal of Rheology

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We attempt to identify the impact of particle stiffness on the shear-thinning behavior exhibited by frictional and adhesive non-Brownian suspensions. To this aim, we compare the rheological behavior of three suspensions whose particles have different Young's moduli.The stiffest particles are Soda-lime glass beads with a Young modulus of 70 GPa. The two other kinds of particles are made of polydimethylsiloxane and have been manufactured using a homemade millifluidic device that allowed us to produce batches of sparsely polydisperse particles with tunable Young modulus: 1.8 MPa for the softest ones and 15 MPa for the stiffest. We show that the observed shear-thinning is mainly caused by the presence of adhesive forces between particles. For each of the three suspensions, the shear-thinning behavior is described by the variation of the jamming volume fraction, φ m , with stress, σ , and the results are interpreted in the light of the model proposed by [Richards et al., J. Rheol. 64(2), 405-412 (2020)]. We show that the magnitude of variation of φ m with σ is greater the lower the particle stiffness. More precisely, in the adhesive regime, decreasing the particle stiffness leads to a significant decrease in the value of the jamming fraction while, as predicted by the JKR theory, the characteristic adhesion stress, σ a , does not vary with stiffness. We finally show that, for stresses much higher than σ a , the suspensions behave like usual frictional suspensions with a viscosity controlled by both the particle volume fraction and the value of the interparticle friction coefficient.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of particle stiffness on shear-thinning of non-Brownian suspensions

Gilbert

Valette

Lemaire

2021

Journal of Rheology

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“…Recent studies have shown that shear-thinning observed in concentrated NBSs was due either to the presence of adhesion forces between particles [70] or to the decrease in the interparticle friction coefficient when the shear stress increases [15,17] or both [71]. These two effects lead to variations in viscosity with shear stress that have very different patterns.…”

Section: Influence Of Surface Functionalization On the Rheological Properties Of Nbss Of µPs Mp1 Mp3 And Mp5mentioning

confidence: 99%

“…First, friction between particles considerably increases the viscosity of suspensions (about 1 order of magnitude for a 50% concentrated suspension) [10,12,14]. Second, recent studies suggest that shear-thinning can be explained by a stress-dependent friction [15][16][17]. It is therefore of utmost importance to control the surface properties of particles, both for applications involving suspension flows and, from a more fundamental point of view, to be able to conduct quantitative studies on the links between rheology and surface properties.…”

Section: Introductionmentioning

confidence: 99%

Cross-linked polymer microparticles with tunable surface properties by the combination of suspension free radical copolymerization and Click chemistry

Moratille

Arshad

Cohen

et al. 2022

Journal of Colloid and Interface Science

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We propose a general, versatile and broad in scope two-steps approach for the elaboration of cross-linked polymer microparticles (µPs) with tunable surface properties and functionalities. Surface-functionalized cross-linked polymer µPs with diameter in the 80 μm range are prepared by the combination of: 1) suspension free radical copolymerization of styrene, propargyl methacrylate and 1,6-hexanediol dimethacrylate, 2) subsequent covalent tethering of a variety of azide-functionalized moieties by copper(I)-catalyzed azide-alkyne cycloaddition (i.e. rhodamine B fluorescent dye or poly(ethylene glycol) brushes) and, 3) optional N-alkylation of the 1,2,3-triazole groups followed by anion exchange reactions to afford covalently-tethered 1,2,3-triazolium ionic liquids with iodide or cresol red as counter-anions. The resulting µPs are characterized by laser diffraction, differential scanning calorimetry, as well as by optical, confocal fluorescence, scanning electron and atomic force microscopies. Finally, the rheological properties of concentrated suspensions (volume fractions of 0.40 and 0.44) of the different synthesized µPs dispersed in a 1:1 (vol/vol) mixture of polalkylene glycol and water are studied.The modification of particles surface properties contributes not only to change the stability of the suspensions against flocculation, but also to significantly modify their rheological behavior at high shear stresses. This last result highlights the importance of non-hydrodynamic contact forces in the rheology of non-Brownian suspensions.

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“…A detailed discussion on the numerical tool and its validation can be found elsewhere. [43][44][45][46] Starting from the equations of motion and calculating the hydrodynamic forces; for a Stokes flow regime, the force balance of particles after neglecting inertia can be described by the following equation…”

Section: Numerical Analysismentioning

confidence: 99%

Sheared Thick‐Film Electrode Materials Containing Silver Powders with Nanoscale Surface Asperities Improve Solar Cell Performance

Hilali

Pal

et al. 2021

Adv Energy and Sustain Res

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Thick-film screen-printed fine-line metallization is one of the most important process steps in the whole production chain of photovoltaic cell manufacturing as variations in industrial solar cell performance mainly depend on electrode properties. The impact of Ag powder surface topography on viscoelastic characteristics and geometry of solar cell electrodes is studied. Numerical simulations for concentrated non-Brownian suspensions show that shear viscosity and storage modulus increase with particle roughness. Experimental rheological analysis shows improvement in thixotropy and shear storage modulus for pseudoplastic electrode materials with corrugated Ag powders. Consequently, viscoelastic recovery is enhanced for frontside electrode gridlines with roughsurface Ag powders. This results in aspect-ratio and cross-sectional symmetry enhancement for rough-surface Ag powder gridlines compared with smoothsurface Ag powder gridlines. Rough-surface Ag powder gridlines have smaller height variations, making them more suitable for high-throughput screen printing. Optical simulations show improved light redirection into the solar cell for gridlines formed from rough-surface Ag powders, leading to higher solar cell photocurrent. The improved gridline definition results in an increase in shortcircuit current density, yielding average efficiency improvement of %0.1% absolute for monocrystalline-Si solar cells with screen-printed gridlines having rough-surface Ag powders. This results in monocrystalline-Si solar cells with 22.45% average conversion efficiency.

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Effect of roughness on the rheology of concentrated non-Brownian suspensions: A numerical study

Cited by 30 publications

References 81 publications

Impact of particle stiffness on shear-thinning of non-Brownian suspensions

Impact of particle stiffness on shear-thinning of non-Brownian suspensions

Cross-linked polymer microparticles with tunable surface properties by the combination of suspension free radical copolymerization and Click chemistry

Sheared Thick‐Film Electrode Materials Containing Silver Powders with Nanoscale Surface Asperities Improve Solar Cell Performance

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