Hardening of particle/oil/water suspensions due to capillary bridges: Experimental yield stress and theoretical interpretation

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Hardening of particle/oil/water suspensions due to capillary bridges : Experimental yield stress and theoretical interpretation. / Danov, Krassimir D.; Georgiev, Mihail T.; Kralchevsky, Peter A.; Radulova, Gergana M.; Gurkov, Theodor D.; Stoyanov, Simeon D.; Pelan, Eddie G.

In: Advances in Colloid and Interface Science, Vol. 251, 01.01.2018, p. 80-96.

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Danov, Krassimir D. ; Georgiev, Mihail T. ; Kralchevsky, Peter A. ; Radulova, Gergana M. ; Gurkov, Theodor D. ; Stoyanov, Simeon D. ; Pelan, Eddie G. / Hardening of particle/oil/water suspensions due to capillary bridges : Experimental yield stress and theoretical interpretation. In: Advances in Colloid and Interface Science. 2018 ; Vol. 251. pp. 80-96.

Bibtex

@article{d54fe9f4deff4069b3b7cb3c84f21b04,
title = "Hardening of particle/oil/water suspensions due to capillary bridges: Experimental yield stress and theoretical interpretation",
abstract = "Suspensions of colloid particles possess the remarkable property to solidify upon the addition of minimal amount of a second liquid that preferentially wets the particles. The hardening is due to the formation of capillary bridges (pendular rings), which connect the particles. Here, we review works on the mechanical properties of such suspensions and related works on the capillary-bridge force, and present new rheological data for the weakly studied concentration range 30–55 vol% particles. The mechanical strength of the solidified capillary suspensions, characterized by the yield stress Y, is measured at the elastic limit for various volume fractions of the particles and the preferentially wetting liquid. A quantitative theoretical model is developed, which relates Y with the maximum of the capillary-bridge force, projected on the shear plane. A semi-empirical expression for the mean number of capillary bridges per particle is proposed. The model agrees very well with the experimental data and gives a quantitative description of the yield stress, which increases with the rise of interfacial tension and with the volume fractions of particles and capillary bridges, but decreases with the rise of particle radius and contact angle. The quantitative description of capillary force is based on the exact theory and numerical calculation of the capillary bridge profile at various bridge volumes and contact angles. An analytical formula for Y is also derived. The comparison of the theoretical and experimental strain at the elastic limit reveals that the fluidization of the capillary suspension takes place only in a deformation zone of thickness up to several hundred particle diameters, which is adjacent to the rheometer's mobile plate. The reported experimental results refer to water-continuous suspension with hydrophobic particles and oily capillary bridges. The comparison of data for bridges from soybean oil and hexadecane surprisingly indicate that the yield strength is greater for the suspension with soybean oil despite its lower interfacial tension against water. The result can be explained with the different contact angles of the two oils in agreement with the theoretical predictions. The results could contribute for a better understanding, quantitative prediction and control of the mechanical properties of three-phase capillary suspensions solid/liquid/liquid.",
keywords = "Capillary bridges, Capillary suspensions, Pendular state, Rheology of suspensions, Wet granular materials, Yield stress",
author = "Danov, {Krassimir D.} and Georgiev, {Mihail T.} and Kralchevsky, {Peter A.} and Radulova, {Gergana M.} and Gurkov, {Theodor D.} and Stoyanov, {Simeon D.} and Pelan, {Eddie G.}",
year = "2018",
month = jan,
day = "1",
doi = "10.1016/j.cis.2017.11.004",
language = "English",
volume = "251",
pages = "80--96",
journal = "Advances in Colloid and Interface Science",
issn = "0001-8686",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Hardening of particle/oil/water suspensions due to capillary bridges

T2 - Experimental yield stress and theoretical interpretation

AU - Danov, Krassimir D.

AU - Georgiev, Mihail T.

AU - Kralchevsky, Peter A.

AU - Radulova, Gergana M.

AU - Gurkov, Theodor D.

AU - Stoyanov, Simeon D.

AU - Pelan, Eddie G.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Suspensions of colloid particles possess the remarkable property to solidify upon the addition of minimal amount of a second liquid that preferentially wets the particles. The hardening is due to the formation of capillary bridges (pendular rings), which connect the particles. Here, we review works on the mechanical properties of such suspensions and related works on the capillary-bridge force, and present new rheological data for the weakly studied concentration range 30–55 vol% particles. The mechanical strength of the solidified capillary suspensions, characterized by the yield stress Y, is measured at the elastic limit for various volume fractions of the particles and the preferentially wetting liquid. A quantitative theoretical model is developed, which relates Y with the maximum of the capillary-bridge force, projected on the shear plane. A semi-empirical expression for the mean number of capillary bridges per particle is proposed. The model agrees very well with the experimental data and gives a quantitative description of the yield stress, which increases with the rise of interfacial tension and with the volume fractions of particles and capillary bridges, but decreases with the rise of particle radius and contact angle. The quantitative description of capillary force is based on the exact theory and numerical calculation of the capillary bridge profile at various bridge volumes and contact angles. An analytical formula for Y is also derived. The comparison of the theoretical and experimental strain at the elastic limit reveals that the fluidization of the capillary suspension takes place only in a deformation zone of thickness up to several hundred particle diameters, which is adjacent to the rheometer's mobile plate. The reported experimental results refer to water-continuous suspension with hydrophobic particles and oily capillary bridges. The comparison of data for bridges from soybean oil and hexadecane surprisingly indicate that the yield strength is greater for the suspension with soybean oil despite its lower interfacial tension against water. The result can be explained with the different contact angles of the two oils in agreement with the theoretical predictions. The results could contribute for a better understanding, quantitative prediction and control of the mechanical properties of three-phase capillary suspensions solid/liquid/liquid.

AB - Suspensions of colloid particles possess the remarkable property to solidify upon the addition of minimal amount of a second liquid that preferentially wets the particles. The hardening is due to the formation of capillary bridges (pendular rings), which connect the particles. Here, we review works on the mechanical properties of such suspensions and related works on the capillary-bridge force, and present new rheological data for the weakly studied concentration range 30–55 vol% particles. The mechanical strength of the solidified capillary suspensions, characterized by the yield stress Y, is measured at the elastic limit for various volume fractions of the particles and the preferentially wetting liquid. A quantitative theoretical model is developed, which relates Y with the maximum of the capillary-bridge force, projected on the shear plane. A semi-empirical expression for the mean number of capillary bridges per particle is proposed. The model agrees very well with the experimental data and gives a quantitative description of the yield stress, which increases with the rise of interfacial tension and with the volume fractions of particles and capillary bridges, but decreases with the rise of particle radius and contact angle. The quantitative description of capillary force is based on the exact theory and numerical calculation of the capillary bridge profile at various bridge volumes and contact angles. An analytical formula for Y is also derived. The comparison of the theoretical and experimental strain at the elastic limit reveals that the fluidization of the capillary suspension takes place only in a deformation zone of thickness up to several hundred particle diameters, which is adjacent to the rheometer's mobile plate. The reported experimental results refer to water-continuous suspension with hydrophobic particles and oily capillary bridges. The comparison of data for bridges from soybean oil and hexadecane surprisingly indicate that the yield strength is greater for the suspension with soybean oil despite its lower interfacial tension against water. The result can be explained with the different contact angles of the two oils in agreement with the theoretical predictions. The results could contribute for a better understanding, quantitative prediction and control of the mechanical properties of three-phase capillary suspensions solid/liquid/liquid.

KW - Capillary bridges

KW - Capillary suspensions

KW - Pendular state

KW - Rheology of suspensions

KW - Wet granular materials

KW - Yield stress

UR - http://www.scopus.com/inward/record.url?scp=85034851562&partnerID=8YFLogxK

U2 - 10.1016/j.cis.2017.11.004

DO - 10.1016/j.cis.2017.11.004

M3 - Review article

AN - SCOPUS:85034851562

VL - 251

SP - 80

EP - 96

JO - Advances in Colloid and Interface Science

JF - Advances in Colloid and Interface Science

SN - 0001-8686

ER -