Rheology and microstructure of graphene oxide reinforced xanthan gum suspensions

Le résumé fourni par la source

Xanthan gum (XG) is a biopolymer extensively utilized as a rheology modifier across several industries, including oil and gas, food, and cosmetics, where enhancements in physicochemical properties are essential. In this context, the addition of nanomaterials such as graphene oxide (GO) can play a key role in the rheological response of XG under different thermophysical conditions. The present work aims to study the effects of the addition of GO nanostructures on the rheology and the microstructure of aqueous suspensions of XG. GO nanosheets were synthesized by the modified Hummers method. The rheological response was obtained through steady-state and oscillatory flow tests to evaluate the effect of GO concentration in a fixed concentration of XG in water under different temperatures and pressures. Samples containing a near saturated concentration of sodium chloride were also analyzed. XG suspensions showed a shear-thinning and viscoelastic response, while the addition of GO leads to a more robust suspension with an increase in shear viscosity and viscoelastic moduli, as well as thermal stability at high temperatures, while at high pressure minimal influence was observed. The addition of sodium chloride displayed an opposite behavior from GO, decreasing its rheological response at low temperatures and having less influence at high temperatures. Flow curves were fitted by a phenomenological model with two power-law regimes. The cryo-micrographs supported the rheological findings and presented a visual depiction of the microstructure of the suspensions. The observed enhancements in viscoelastic properties and thermal stability offer promising paths for the development of advanced functional fluids.

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