| Summary: | In this article, different methods are investigated for the preparation of nanofluids composed of hydrocolloid xanthan gum (XG) and hydrophilic silica nanoparticles (NP) dispersed in water. The rheological behavior of the XG solutions and NP suspensions was first characterized individually, for different concentrations. The effect of the presence of salt (NaCl) was then evaluated. The polymer dilution curves were established, delimiting the dilute and semi-dilute regimes. Different preparation methods of the nanofluids were then considered, testing different factors like the hydration time of the polymer, the sonication time, and the order of aggregation of the components (XG - NP). Characterization techniques such as dynamic light scattering (DLS) and rheological characterization at constant temperature and variable shear rate were used, providing a trend in the stability of the viscous profile of nanofluids. The simplest method providing a correct dispersion of the NP as well as the increase of the viscous profile was then selected. Finally, the evolution in time of the nanofluids was studied and it was observed that the presence of NP stabilized the polymer solution by maintaining its viscosity level in time. This study provides a better understanding of the interactions between XG and silica NP in solution, through the rheological behavior of fluids at low concentrations.
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