Rheology of suspensions of hydrophilic and hydrophobic solid particles in nonaqueous media

Diemen, van Ajg Alois; Schreuder, Fwam; Stein, H.N.

doi:10.1016/0021-9797(85)90012-8

Cited by 14 publications

(5 citation statements)

References 21 publications

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“…However, in contrast to these observations, in some suspensions with coarse particles (mainly glass beads and coal particles of 10 to 100 microns), at volume fractions of filler close to &,, dilatancy is not observed (16,17,(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). Lack of information on the important particle size distribution (34).…”

Section: Background On Dilatancymentioning

confidence: 80%

Dilatancy of concentrated suspensions with Newtonian matrices

Yilmazer

Kalyon

1991

Polymer Composites

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Suspensions filled close to their maximum packing fraction present special challenges in their processing and in their rheological characterization. In this report, the literature in the area of dilatancy of concentrated suspensions is reviewed. Furthermore, the shear viscosity of a Newtonian polymeric liquid filled with 60 vol. percent of ammonium sulfate has been investigated. Both capillary and parallel disk torsional flows, were employed, spanning three decades in shear stress. Upon correction for slip, the suspension exhibited shear thinning at low shear stresses and shear thickening at higher shear stresses. Above a critical wall shear stress, the shear viscosity of the suspension increased unboundedly and the flow became pluglike with apparent slip at the wall. These findings have important ramifications in the processing of composites from such concentrated suspensions.

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Section: Background On Dilatancymentioning

confidence: 80%

Dilatancy of concentrated suspensions with Newtonian matrices

Yilmazer

Kalyon

1991

Polymer Composites

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“…It should be remarked, however, that their dispersions contained particles in a size range (30-100 gm) in which colloidal forces are dominated by viscous and body forces (e.g., gravity). In the case of Schreuder's dispersions, the predominance of viscous forces was evidenced by arguments from energy dissipation (26) and from the viscosity at high shear rates. Because our dispersions contain smaller particles with much higher stabilizing forces the effects seen in our measurements are more severe and can also be studied in a wider range.…”

Section: Discussionmentioning

confidence: 99%

Viscoelastic properties of concentrated shear-thickening dispersions

Boersma

Lavèn

Stein

1992

Journal of Colloid and Interface Science

119

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The viscoelastic properties of electrostatically stabilized concentrated dispersions of silica and of glass particles in a glycerol/water mixture are studied by oscillatory shear measurements. These dispersions are shear-thickening in steady shear flow. At most frequencies the loss modulus is found to dominate the storage modulus. At certain critical combinations of deformation amplitude and frequency the response signal becomes distorted, containing higher harmonics. This phenomenon can be ascribed to flow blockage, closely related to shear thickening in steady shear flow. When plotting the critical deformation against the frequency, three different regions can be detected. At low frequencies there is the steady shear flow limit, at intermediate frequencies double-layer overlap causes nonlinearity in the response signal, and at high frequencies there is a region where the critical deformation for flow blockage is a system-dependent function of the frequency, but is independent of the volume fraction. The magnitudes of the storage moduli are found to be in reasonable agreement with theoretical predictions.

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“…In such suspensions, no rheologically measurable coagulation is found [8]. The values of /']diff//~0 for ~ ~ o% obtained in those cases [9], are mentioned in the caption to figure 3.…”

Section: Analysis Of Behaviour At High Shear Ratesmentioning

confidence: 90%

“…It has been determined by Hunter from the effective solid volume fraction in the Dougherty-Krieger relation [7]: [8,9]. In addition, the general validity of ~Omax = 0.60 for suspensions with aggregates of different sizes must be doubted as well.…”

Section: Introductionmentioning

confidence: 99%

Rheology of concentrated coagulating suspensions in non-aqueous media

Schreuder¹,

Stein

1987

Rheol Acta

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The rheology of concentrated coagulating suspensions is analysed on the basis of the following model: (i) at low shear rates, the shear is not distributed homogeneously but limited to certain shear planes; (ii) the energy dissipation during steady flow is due primarily to the overcoming of viscous drag by the suspended particles during motion caused by encounters of particles in the shear planes. This model is called the "giant floc" model.With increasing shear rate the distance between successive shear planes diminishes, approaching the suspended particles' diameter at average shear stresses of 88-117 Pa in suspensions of 78 lam particles (glass ballotini coated by a hydrophobic layer) in glycerol -water mixtures, at solid volume fractions between 0.35 and 0.40. Smaller particles form a more persistent coagulation structure. The average force necessary to separate two touching 78 gm particles is too large to be accounted for by London-van der Waels forces; thus coagulation is attributed to bridging connections between polymer chains protruding from the hydrophobic coatings.The frictional ratio of the glass particles in these suspensions is of the order of 10. Coagulation leads to build-up of larger structural units at lower shear rates; on doubling the shear rate the average distance between the shear planes decreases by a factor of 0.81 to 0.88.

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Rheology of suspensions of hydrophilic and hydrophobic solid particles in nonaqueous media

Cited by 14 publications

References 21 publications

Dilatancy of concentrated suspensions with Newtonian matrices

Dilatancy of concentrated suspensions with Newtonian matrices

Viscoelastic properties of concentrated shear-thickening dispersions

Rheology of concentrated coagulating suspensions in non-aqueous media

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