Instrumental characterization of xanthan gum and scleroglucan solutions: Comparison of rotational rheometry, capillary breakup extensional rheometry and soft-contact tribology

Host-guest strategy improves rheological properties, conformational stability and oil displacement efficiency of xanthan gum

The low cost and environmental advantages of Xanthan gum make its production and application scale exceed that of other polysaccharides. However, the temperature resistance of Xanthan gum limits its application. In this study, polysaccharide supramolecular Xanthan gum network (XG-β-CD/AD) based on β-cyclodextrin and adamantane was prepared for enhanced oil recovery. The structure of Xanthan gum was characterized by Fourier infrared spectroscopy, nuclear magnetic resonance spectroscopy and thermogravimetric analysis. The rheological properties of the modified polysaccharide network in aqueous solution were systematically studied. The results showed that physical cross-linking of host-guest interacion enhanced the thickening ability of the polymer. Shear rheology, extensional rheology and dynamic modulus test proved that XG-β-CD/AD had excellent rheological properties. The micromorphology, dynamic light scattering and circular dichroism clarified the molecular conformation, the host-guest interaction can improve conformational transition temperature (Tm) and inorganic salt tolerance of Xanthan gum. Under harsh environment (90 °C, 30000 mg/L brine), the oil recovery of XG-β-CD/AD is 6 %-11 % higher than that of XG at the same conditions, showing a better ability to improve the recovery rate. This study provides a research idea for the selection, development and application of biomacromolecular materials.

Effect of Fucoidan on Conformation of Xanthan Gum and Its Tribo-Rheological Properties

This study sought to explore the rheological and tribological properties of fucoidan-xanthan gum (XG) mixtures at different fucoidan concentrations. A conformational transition of XG from disordered to ordered forms was observed with an increasing fucoidan concentration, as determined by intrinsic viscosity measurements and Fourier transform infrared analysis. All mixtures exhibited non-Newtonian flow behavior with the yield stress. The mixture sample with 0.5% fucoidan displayed higher apparent viscosity at 100 s-1, yield stress, and viscoelastic moduli values than XG alone, suggesting viscoelastic synergism between the two biopolymers. However, these values exhibited a decreasing trend with higher fucoidan concentrations (0.5-2.0%), indicating a nullification of synergism. While XG alone exhibited antithixotropic behavior, fucoidan-XG mixtures showed thixotropic behavior, most pronounced at 1.0% fucoidan. A decreasing trend was observed in the maximum friction coefficient as the fucoidan concentration increased, indicating better lubricant properties. Collectively, our findings may enable widespread adoption and application of fucoidan in various industries.