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Rheological studies of concentrated guar gum
Marija Oblonšek, Sonja Šostar-Turk, Romano Lapasin, 2003, original scientific article

Abstract: Polymers and surfactants are essential ingredients of the printing paste. Polysaccharides are used commercially to thicken, suspend or stabilise aqueoussystems. Also they are used to produce gels and to act as flocculates, binders, lubricants, to serve as modifiers of film properties, and have a function as adjusters of rheological parameters. Surfactants, on the other hand, perform numerous functions acting as dispersants, wetting agents, emulsifiers and antifoaming agents. The rheological properties of polysaccharide thickeners (guar gums with different substitution levels and different producers) at different concentrations and temperatures and, second,the effects produced by the addition of nonionic surfactants (polyoxyethylene stearyl alcohols with different numbers of EO groups) have been studied under linear and nonlinear shear conditions. Experimental data have been correlated with the different modelsČ flow curves with the Cross, Carreau and Meter-Bird model, and mechanical spectra with the generalized Maxwell model and Friedrich-Braun model. The surface tensions of aqueous systems containing polysaccharide andžor surfactants have been determined overextended concentration ranges in order to detect the CMC conditions and toprovide a better understanding about the polysaccharide-surfactant interactions.
Keywords: textile printing, printing pastes, polysaccharides, thickeners, rheology, viscoelasticity, surfactants, guar gum
Published in DKUM: 01.06.2012; Views: 2589; Downloads: 88
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Rheological study of interactions between non-ionic surfactants and polysaccharide thickeners used in textile printing
Rebeka Fijan, Sonja Šostar-Turk, Romano Lapasin, 2007, original scientific article

Abstract: The influence of four non-ionic surfactants (isododecyl and cetyl polyoxyethylene ethers) on aqueous polysaccharide solutions (sodium alginate, guar gum, and sodium carboxymethyl guar), applicable for textile printing pastes, were studied via rheological measurements. Rheology of polysaccharide-surfactant solutions in aqueous matrices is primarily governed by polymer content, which imparts marked shear-thinning and viscoelastic character to the system. Such properties are modulated in moderate but sensible way by changes in surfactant concentration or type. Above 3% surfactants addition to non-substituted guar gum solutions results in a significant impact leading to phase separation and a particular strongly associated phase is formed due to hydrogen bonds between ethylene oxy units from the surfactant and primary hydroxyl groups in guar. A satisfactory fitting of viscosity data is obtained with both the Cross equation and the Roberts-Barnes-Carew model. The experimental results of mechanical spectra can be described quite satisfactory with both the Friedrich-Braun and the generalized Maxwell models.
Keywords: textile printing, polysaccharide thickeners, rheology, non-ionic surfactant, polymer-surfactant interactions, viscoelasticity
Published in DKUM: 01.06.2012; Views: 2016; Downloads: 91
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A study of rheological and molecular weight properties of recycled polysaccharides used as thickeners in textile printing
Rebeka Fijan, Michele Basile, Sonja Šostar-Turk, Ema Žagar, Majda Žigon, Romano Lapasin, 2009, original scientific article

Published in DKUM: 01.06.2012; Views: 2145; Downloads: 81
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