Changements de structure provoqués par l'écoulement

Joly, M.

doi:10.1007/bf01968863

Cited by 6 publications

(2 citation statements)

References 13 publications

(3 reference statements)

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“…If at the flow of polymer solutions the cooperative motion of polymer coils is partly approximated by their independent motion (in the solutions under investigation at the concentration 0.02 gcm -3 such an approximation can be regarded as acceptable), the frequency relation may be described by the Joly equation [13] derived for the frequency of collisions between two spherical particles in the hydrodynamic field. According to this equation, the frequency factor is a sum of two terms, viz., fl which corresponds to collisions caused by thermal motion fl = (2k/3x)(T/11s), and f2 which ensues from collisions caused by flow,…”

Section: Relationship Between Conditions Of the Phenomenon And Inductmentioning

confidence: 99%

Criteria of negative thixotropy of poly(methyl methacrylate) solutions as a function of temperature and of the thermodynamic quality and viscosity of the solvent

Bradna¹,

Quadrat

1984

Colloid & Polymer Sci

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A study of the effect of thermodynamic quality and viscosity of the solvent and of temperature on the negative thixotropy of poly(methyl methacrylate) solutions using criteria suggested in the preceding paper showed that the minimal shear stress is a more general criterion of hydrodynamic conditions of the formation of this effect than the minimal velocity gradient. It is assumed that the occurrence of negative thixotropy is due to the activation of macromolecules combined with their critical deformation and orientation caused by the effect of a certain minimal shear stress. A general quantitative relationship between the induction period and conditions of formation of the negative thixotropic structure was derived and experimentally tested.Key words: Negative thixotropy-dependence on solvent power and its viscosity, nonNewtonian flow of poly(methyl methacrylate solutions.

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Section: Relationship Between Conditions Of the Phenomenon And Inductmentioning

confidence: 99%

Criteria of negative thixotropy of poly(methyl methacrylate) solutions as a function of temperature and of the thermodynamic quality and viscosity of the solvent

Bradna¹,

Quadrat

1984

Colloid & Polymer Sci

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“…The pseudoplastic behavior observed at very low rates of shear is explained on the basis of floc disruption; whereas, the dilatant behavior at high shear rates is explained on the basis of floc formation. This apparent anomaly can be resolved by considering pseudoplasticity and dilatancy as competitive rate processes.The equations to follow were used by Joly(54) to describe the kinetics of flocculation in a colloidal suspension. Joly's analysis is similar to that proposed by Blatz and Tobolsky (53) to describe the kinetics of a linear polymer system manifesting simultaneous polymerization and depolymerization.…”

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confidence: 99%

A Study of the Phenomenon of Rheological Dilatancy in an Aqueous Pigment Suspension

Morgan¹

1968

Transactions of the Society of Rheology

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The objective of this study was to gain a better understanding of the mechanisms responsible for rheological dilatancy in an aqueous pigment suspension. Of particular interest was the relationship between the extent of dilatancy and colloidal stability. This relationship was studied using iron oxide suspensions which were dispersed by addition of sodium polymethacrylate having a molecular weight of 4000. The level of colloidal stability was varied by changing the degree of dissociation of the carboxyl groups on the polymer. Measurements of the extent of adsorption of the dispersant were made and the adsorbed charge was found to correlate very well with low-shear viscosity measurements. Additional experiments were made to determine the effect of pigment volume concentration on dilatancy over the range of 40–47%. A cup-and-bob viscometer was used to measure the shear stress over a shear rate range of 100–4000 sec−1. The extent of rheological dilatancy was found to increase with (a) decreasing colloidal stability, and (b) increasing pigment concentration. Based on these findings, it was postulated that rheological dilatancy results from a progressive increase in flocculation due to shear. The fact that a suspension can exhibit both pseudoplasticity and dilatancy was explained by considering floc formation and floc disruption as competitive rate processes.

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Unstable flows of concentrated suspensions

Quemada

Stability of Thermodynamics Systems

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Changements de structure provoqués par l'écoulement

Cited by 6 publications

References 13 publications

Criteria of negative thixotropy of poly(methyl methacrylate) solutions as a function of temperature and of the thermodynamic quality and viscosity of the solvent

Criteria of negative thixotropy of poly(methyl methacrylate) solutions as a function of temperature and of the thermodynamic quality and viscosity of the solvent

A Study of the Phenomenon of Rheological Dilatancy in an Aqueous Pigment Suspension

Unstable flows of concentrated suspensions

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