The rheological properties of Guar Gum hydrogels having chemical and physical transient cross-links simultaneously (dual cross-link gels) were studied. Hydrogels were prepared by mixing an aqueous solution of guar gum with montmorillonite and using glutaraldehyde as crosslinking agent. Preliminary XRD analysis indicated that an exfoliated structure was formed in presence of small amounts of clay. For the sample with a higher clay content (5 wt 103 % w/w) the formation of micro-scale composites (tactoids) is favored. Dynamic oscillatory analyses showed that all the samples exhibit a gel behavior as the elastic modulus is always bigger than the viscous one. Moreover, G’’ is characterized by a peak more pronounced for the hydrogel with 2.5% w/w of clay. This trend, typical of a physical gel, can be ascribed to the higher density of transient entanglements induced by the presence of the exfoliated clay inside the polymer matrix.

Structural and rheological characterization of chemically crosslinked guar gum and organically modified montmorillonite hydrogels

BRANCA, Caterina;VISCO, Annamaria;D'ANGELO, Giovanna;WANDERLINGH, Ulderico
2013-01-01

Abstract

The rheological properties of Guar Gum hydrogels having chemical and physical transient cross-links simultaneously (dual cross-link gels) were studied. Hydrogels were prepared by mixing an aqueous solution of guar gum with montmorillonite and using glutaraldehyde as crosslinking agent. Preliminary XRD analysis indicated that an exfoliated structure was formed in presence of small amounts of clay. For the sample with a higher clay content (5 wt 103 % w/w) the formation of micro-scale composites (tactoids) is favored. Dynamic oscillatory analyses showed that all the samples exhibit a gel behavior as the elastic modulus is always bigger than the viscous one. Moreover, G’’ is characterized by a peak more pronounced for the hydrogel with 2.5% w/w of clay. This trend, typical of a physical gel, can be ascribed to the higher density of transient entanglements induced by the presence of the exfoliated clay inside the polymer matrix.
2013
9788896398074
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/2660570
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