Rheology of Xanthan Gum: Salt, Temperature, and Strain Effects in Oscillatory and Steady Shear Experiments

Rochefort, Willie E.; Middleman, Stanley

doi:10.1122/1.549953

Cited by 263 publications

(149 citation statements)

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“…These two groups of chemicals are normally present in the concentrate at levels of around 3 and 1%, respectively. Salts of alkaline metals (e.g., NaCl) are known to affect the rheological properties of xanthan gum solutions [6] by facilitating conformation transformations (disorder → order) of polymer chains [7][8][9], and we expect similar behaviour to operate for the present material as well, owing to the presence of organic salts.…”

Section: Methodsmentioning

confidence: 81%

Friction Factors For Pipe Flow Of Xanthan- Based Concentrates Of Fire Fighting Foams

Dlugogorski¹,

Schaefer²,

Kennedy³

2005

Fire Safety Science - Proceedings of the Eigth International Sy

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In this paper we develop a friction factor correlation to predict the pressure drop during pumping and induction of concentrates of fire fighting foams containing around 1% of xanthan gum. Such concentrates are highly elastic, display small yield stress and exhibit significant thinning upon shearing. We demonstrate that in the turbulent regime, the Blasius equation normally used for Newtonian fluids seems to correlate well the friction factor with the Metzner-Reed Reynolds number. Our development provides an example of how the methodology used to develop the friction factor correlation can be applied to analyse a set of experimental data to verify its internal consistency. The friction factors developed in the paper can be applied to other foam concentrates that include a similar content of xanthan gum in their formulation, to predict pressure drop as a function of a flow rate and pipe diameter, provided that there exists an appropriate viscosity model. Subsequently, the paper presents experimental measurements of apparent viscosity for one foam concentrate and develops relevant viscosity models. We observe that the rheology of the concentrate is governed by the behaviour of xanthan gum. Although, the foam concentrate considered in the article is yield pseudo plastic (i.e., it follows the Herschel-Bulkley model), for the shear stresses normally encountered during pipe flow, the viscosity of the material can be described by a power law model. Over the temperature range of between 0 and 40 o C, the apparent viscosity displays only a weak dependence on temperature. Subsequent calculations of pressure drop with temperature demonstrate minor variation in pressure drop with temperature, but only in the turbulent flow regime. This suggests that induction systems intended to operate under widely varying temperature conditions should be designed to function in the turbulent flow regime.

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Section: Methodsmentioning

confidence: 81%

Friction Factors For Pipe Flow Of Xanthan- Based Concentrates Of Fire Fighting Foams

Dlugogorski¹,

Schaefer²,

Kennedy³

2005

Fire Safety Science - Proceedings of the Eigth International Sy

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“…This behavior was not observed for xanthan because the temperature range used was not sufficient for conformational changes to occur in this polymer and the rheological properties remained practically constant (Rochefort and Middleman, 1987). Moreover, the activation energy decreased at higher xanthan concentrations, making the effect of temperature on the rheological properties less significant, which could be justified by the increase in polymer-polymer interactions and lower molecular mobility.…”

Section: Steady Shear Rheologymentioning

confidence: 83%

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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“…A solução estoque de 2% em peso de xantana em água bidestilada foi preparada usando um agitador de lâminas a baixa velocidade por 10 minutos [8] . A solução foi armazenada a aproximadamente 2 °C por um período de 48 horas antes do uso.…”

Section: Soluçõesunclassified

“…Devidas as suas propriedades reológicas únicas, este polissacarídeo é muito utilizado como agente de suspensão, espessante, emulsificante e estabilizante, na indústria de alimentos [1][2][3] , bem como na indústria de petróleo, como agente de recuperação [4][5][6][7] . A goma xantana é um polieletrólito, que em solução, suas propriedades e configuração molecular modificam por forças iônicas [8,9] . Em soluções aquosas, por exemplo, sob aquecimento entre 27 e 86 °C, a goma xantana sofre uma mudança conformacional de hélice parcialmente ordenada para conformação desordenada; por outro lado, sob resfriamento, entre 86 e 32 °C, a macromolécula muda de conformação ordenada para formação de rede.…”

Section: Introductionunclassified

“…Quando se adiciona NaCl, a mudança conformacional é outra; sob aquecimento, entre 30 e 86 °C, somente uma configuração em hélice organizada está presente. Sob resfriamento, no entanto, entre 86 e 35 °C, a mudança conformacional parte da hélice organizada para hélices fraturadas com formação de redes [8,[10][11][12] . As propriedades reológicas dinâmicas das soluções de goma xantana foram estudadas por outros autores para a determinação dos efeitos da concentração e temperatura sobre sua estrutura conformacional [13][14][15][16] .…”

Section: Introductionunclassified

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Caracterização reológica da goma xantana: influência de íons metálicos univalente e trivalente e temperatura em experimentos dinâmicos

Luporini¹,

Bretas

2011

Polímeros

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Resumo: As propriedades dinâmicas das soluções aquosas de goma xantana com e sem adição de NaCl ou Al 2 (SO 4 ) 3 .18H 2 O foram medidas em um reômetro de deformação controlada aplicando ciclos de aquecimento e resfriamento. O tempo de relaxação decresceu com o aumento da temperatura; no entanto, este tempo aumentou com a adição de sal nas soluções de 0,5% em peso de goma xantana, mas diminuiu com a adição de 1%. Durante o aquecimento das soluções de goma xantana pura ocorreu uma mudança de conformação a 51 °C, e durante o resfriamento foi observada a formação de duas estruturas: entre 86 e 47 °C e abaixo de 47 °C. Com a adição de sal não houve mudança conformacional durante o aquecimento, enquanto no resfriamento duas estruturas foram novamente observadas, mas para faixas de temperatura diferentes. Palavras-chave: Xantana, mudança conformacional, reologia, gel, viscoelasticidade. Rheological Characterization of Xanthan Gum: Influence from Univalent and Trivalent Metallic Ions and From the Temperature in Dynamic ExperimentsAbstract: The dynamic rheological properties of water xanthan gum solutions with and without the addition of NaCl or Al 2 (SO 4 ) 3 .18H 2 O were measured in a strain controlled rheometer applying heating and cooling cycles. The terminal relaxation time decreased with increasing temperature. This time increased with the addition of 0.5 wt. (%) of salt, but decreased when 1 wt. (%) was added. During heating a conformational change occurred at 51 °C and upon cooling two structures were observed between 86 and 47 °C and below 47 °C. When salt was added there was no conformational change during heating, but the two structures again appeared during cooling, though at different temperature ranges.

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Rheology of Xanthan Gum: Salt, Temperature, and Strain Effects in Oscillatory and Steady Shear Experiments

Cited by 263 publications

References 0 publications

Friction Factors For Pipe Flow Of Xanthan- Based Concentrates Of Fire Fighting Foams

Friction Factors For Pipe Flow Of Xanthan- Based Concentrates Of Fire Fighting Foams

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

Caracterização reológica da goma xantana: influência de íons metálicos univalente e trivalente e temperatura em experimentos dinâmicos

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