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

Enhanced oil recovery via dual cross-linked polysaccharide network for superior rheology and flow efficiency

Welan gum has been widely used in harsh reservoir development, such as good thickening ability, temperature and salt resistance. However, viscoelasticity is crucial to polymer injectability and microscopic displacement efficiency, Welan gum have rigid helical conformation and show poor rheological properties., therefore, we proposed a double network strategy to improve the molecular conformation and rheological properties of Welan gum. Specifically, we synthesized β-cyclodextrin functionalized polyacrylamide (HPAM-CD) and adamantane modified Weland gum (WL-AD), and polyacrylamide and Welan gum through the supramolecular interaction to obtain double network crosslinking system (WL-AD&HPAM-CD). Rheology show that the double-network system driven by multiple non-covalent interaction has excellent rheological properties. Circular dichroism, atomic force microscopy and scanning electron microscope show that WL-AD&HPAM-CD forms a special molecular conformation, significantly improve the molecule elasticity of biopolymers, it has good conformational stability under harsh conditions. Therefore, oil recovery rate of WL-AD&HPAM-CD after water flooding in 200 mD cores is 4.99 % and 11.5 % higher than that of the same concentration of Welan gum and grafted Welan gum. In addition, WL-AD&HPAM-CD has excellent fluidity in 10-50 mD low permeability reservoirs, and can increase oil recovery by 12.17-17.16 % after water flooding. This study provides a research ideas for the development and application of biopolymers.

Development and Characterization of Niaprazine-Loaded Xanthan Gum-Based Gel for Oral Administration

Niaprazine is a sedative-hypnotic drug initially developed as an antihistamine and used for its notable sedative effects, particularly in children. Following its withdrawal from the market by the producer, the drug has been administered as magistral formulations available in syrup form, but there are several important disadvantages to this, including instability, taste issues, lack of controlled release, and the potential for unreliable dosing due to incomplete swallowing. There is also an increased risk of dental caries, as well as the fact that these formulations are not suitable for children who suffer from diabetes. The purpose of the current investigation is to prepare and characterize xanthan gum-based gels for the oral administration of niaprazine. Niaprazine gels appear as transparent-whiteish, non-sticky substances, with the drug uniformly dispersed throughout the systems. They are also stable over time. Dynamic rheology revealed their advantageous shear-thinning properties, which enable the formulation to be flexibly dosed orally through administration via syringe. During experimentation, the evaluation of the mucoadhesion features and the in vitro drug release profile were also performed. The results demonstrate that the formulation may represent an alternative to niaprazine syrup, allowing easy preparation, administration, and increased compliance in various categories of patients, including pediatric.

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.