Influence of sodium polyacrylate on the rheology of aqueous Laponite dispersions

Labanda, Jordi; Llorens, Joan

doi:10.1016/j.jcis.2005.03.055

Cited by 54 publications

(22 citation statements)

References 34 publications

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“…Breakdown kinetic constant values decrease as the shear rate increases for both theoretical equations and for 21°Brix peach puree, following a power law dependency, as it was observed by other authors for clays solutions (Labanda and Llorens 2005). A high kinetic constant parameter is characteristic of a fast kinetic process, which means that the shear stress reaches the corresponding equilibrium faster at the fixed shear rate.…”

Section: Resultssupporting

confidence: 81%

Rheological Characterization of Peach Purees

Massa

González

Maestro

et al. 2010

Journal of Texture Studies

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In this work, two commercial peach purees (21 and 11.9°Brix) industrially obtained have been studied at several temperatures involved in industrial processes. Viscoelastic functions were that of a weak gel, and decreased with temperature and increased with concentration. Rheograms were obtained in order to determine the yield stress, which is related to stability against settling during storage. Herschel–Bulkley equation was used to determine the consistency index and the flow index. Thixotropy was quantified by means of one empirical equation (Weltmann model) and two theoretical equations (Figoni–Shoemaker and Tiu–Boger models), which describe the first‐ and second‐order kinetic process of structure breakdown. Both peach purees show thixotropy under nonsteady conditions. The broken‐down structure increased with the applied shear rate and, practically, decreased as the temperature was increased for both peach purees. The breakdown kinetic constants decreased as the shear rate was increased for both theoretical equations following a power law dependency. PRACTICAL APPLICATIONS It is necessary to know the thixotropic behavior of peach purees, since knowledge of the rheological properties is very important in order to improve the design, manipulation and calculation of all those unit operations during the process (i.e., agitation and filtration) and design equipment (i.e., pump systems and pipe sizing), mainly those based on heat and quantum transfer.

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Section: Resultssupporting

confidence: 81%

Rheological Characterization of Peach Purees

Massa

González

Maestro

et al. 2010

Journal of Texture Studies

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“…The proposed model is based on the assumption that viscosity is a direct measure of internal structure and therefore no theoretical parameter such as the structural parameter is needed [11]. A second order kinetic equation is proposed to describe the net kinetic process.…”

Section: Theorymentioning

confidence: 99%

A simple model to describe the thixotropic behavior of paints

Armelín¹,

Martí²,

Rudé³

et al. 2006

Progress in Organic Coatings

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We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.

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“…The ramp usually consists of a series of discrete successive shear-rate or stress steps, each one associated with a certain waiting time, the time during * antti.puisto@aalto.fi which the shear rate is held constant. Depending on the waiting time, the number of shear-rate steps taken, and the material, the hysteresis loop is observed to have different shapes and areas [12][13][14]. The appearance of dynamical hysteresis in rheological data is classically taken as a sign of thixotropy.…”

Section: Introductionmentioning

confidence: 99%

Dynamic hysteresis in the rheology of complex fluids

Puisto

Mohtaschemi²,

Alava³

et al. 2015

Phys. Rev. E

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Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak.

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Influence of sodium polyacrylate on the rheology of aqueous Laponite dispersions

Cited by 54 publications

References 34 publications

Rheological Characterization of Peach Purees

Rheological Characterization of Peach Purees

A simple model to describe the thixotropic behavior of paints

Dynamic hysteresis in the rheology of complex fluids

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