Concentration regimes in xanthan gum solutions deduced from flow and viscoelastic properties

Cuvelier, Gérard; Launay, B.

doi:10.1016/0144-8617(86)90023-8

Cited by 147 publications

(79 citation statements)

References 29 publications

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“…39 Instead, we found s R z (c/c*) 7 which suggests that the relaxation time of xanthan in this concentration range is not simply set by reptation. Such an anomaly has been observed before, [40][41][42][43] and is related to the tendency of xanthan to form double helices that connect two chains with each other. 42,44,45 These physical crosslinks break and reform continuously.…”

Section: Mechanical Propertiesmentioning

confidence: 94%

Origin of suppressed demixing in casein/xanthan mixtures

et al. 2012

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We explore the properties of casein/xanthan mixtures for xanthan concentrations beyond those inducing phase separation. Previous work has successfully described the onset of demixing by depletion theory in the protein limit, where the xanthan polysaccharides, the polymers, are larger than the caseins from skim milk powder, the colloids (S. Bhat et al., J. Phys.: Condens. Matter, 2006, L339). We now extend these studies to xanthan concentrations in a range of c/c* ¼ 13-88, aiming to arrest the phase separation via a (transiently) arrested casein-rich phase. Surprisingly, we find that the casein-rich phase remains fluidic deep into the two-phase region, with an equilibrium composition that significantly differs from predictions for mixtures of hard spheres plus flexible polymer chains in a good solvent. Furthermore, we show that macroscopic phase separation is arrested for c/c* > 60. Our investigations reveal that the rheological properties of the mixtures are fully determined by the xanthan-rich phase with characteristic long relaxation times that depend remarkably strongly on the xanthan concentration.

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Section: Mechanical Propertiesmentioning

confidence: 94%

Origin of suppressed demixing in casein/xanthan mixtures

et al. 2012

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“…This departure from the Cox-Merz rule could be explained by structural damage due to the excessive shear used to obtain the flow curves (Chamberlain and Rao, 1999). For xanthan, this behavior could be attributed to disruption of the hydrogen bonds that associate their chains and that were disrupted at high deformation during the steady shear rate (Cuvelier and Launay, 1986). For the galactomannans, this could be explained by structural decay due to the effect of the stress deformation applied to the system by oscillatory or steady shear (Chamberlain and Rao, 1999).…”

Section: The Cox-merz Rulementioning

confidence: 99%

Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)

Moraes

Fasolin

Cunha

et al. 2011

Braz. J. Chem. Eng.

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-Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady-shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5-35 o C. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G' and G" moduli than the variation in temperature.

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“…Both the molecular structure as well as the rheology of Xanthan gum has been extensively characterized by Cuvelier and Launay (1986), Whitcomb andMacosko (1978), Rochefort andMiddleman (1987), Ross-Murphy, Morris, and Morris (1983) and Tako (1992), amongst others. The Xanthan gum used in this study was sourced from Sigma-Aldrich (SKU: G1253) in powder form.…”

Section: Methodsmentioning

confidence: 99%

A fractional K-BKZ constitutive formulation for describing the nonlinear rheology of multiscale complex fluids

Jaishankar

McKinley

2014

Journal of Rheology

134

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The relaxation processes of a wide variety of soft materials frequently contain one or more broad regions of power-law-like or stretched exponential relaxation in time and frequency. Fractional constitutive equations have been shown to be excellent models for capturing the linear viscoelastic behavior of such materials, and their relaxation modulus can be quantitatively described very generally in terms of a Mittag-Leffler function. However, these fractional constitutive models cannot describe the nonlinear behavior of such power-law materials. We use the example of Xanthan gum to show how predictions of non-linear viscometric properties such as shear-thinning in the viscosity and in the first normal stress coefficient can be quantitatively described in terms a nonlinear fractional constitutive model. We adopt an integral K-BKZ framework and suitably modify it for power-law materials exhibiting MittagLeffler type relaxation dynamics at small strains. Only one additional parameter is needed to predict nonlinear rheology, which is introduced through an experimentally measured damping function. Empirical rules such as the Cox-Merz rule and Gleissle mirror relations are frequently used to estimate the nonlinear response of complex fluids from linear rheological data. We use the fractional model framework to assess the performance of such heuristic rules and quantify the systematic offsets, or shift factors, that can be observed between experimental data and the predicted nonlinear response. We also demonstrate how an appropriate choice of fractional constitutive model and damping function results in a nonlinear viscoelastic constitutive model that predicts a flow curve identical to the elastic Herschel-Bulkley model. This new constitutive equation satisfies the Rutgers-Delaware rule. that is appropriate for yielding materials. This K-BKZ framework can be used to generate canonical three-element mechanical models that provide nonlinear viscoelastic generalizations of other empirical inelastic models such as the Cross model. In addition to describing nonlinear viscometric responses, we are also able to provide accurate expressions for the linear viscoelastic behavior of complex materials that exhibit strongly shearthinning Cross-type or Carreau-type flow curve. The findings in this work provide a coherent and quantitative way of translating between the linear and nonlinear rheology of multiscale materials, using a constitutive modeling approach that involves only a few material parameters.

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Concentration regimes in xanthan gum solutions deduced from flow and viscoelastic properties

Cited by 147 publications

References 29 publications

Origin of suppressed demixing in casein/xanthan mixtures

Origin of suppressed demixing in casein/xanthan mixtures

Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)

A fractional K-BKZ constitutive formulation for describing the nonlinear rheology of multiscale complex fluids

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