Yielding and rheopexy of aqueous xanthan gum solutions

Xanthan gum (XG) is widely used in cosmetic and pharmaceutic products (creams, pastes) oil industry (drilling fluids) as a stabilizing and/or thickening agent. In literature, its rheological behavior mainly presented that of shear-thinning or yield stress fluid. Here, order to clarify this behavior, we study detail the flow characteristics during continued under given conditions (i.e., controlled stress) for mass concentration ranging from 0.2 5%. We are thus able identify apparent curve material after short duration steady state long duration). The validity curve, determined standard rheometry, confirmed by magnetic resonance velocimetry. These materials start exhibit beyond some critical xanthan salt concentration. case, significant increase (by factor up 5) viscosity observed range stresses, before reaching state. This original rheopectic effect might be due, time associated with deformation reconfiguration XG molecules, progressive formation intermolecular links such hydrogen bonds association due acetate residues.