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Abstract
Aqueous dispersions of α‐cellulose are inherently unstable, behaving as lyophobic colloids. The purpose of the present study is to investigate the nature of surface charges (positive or negative) on the dispersed particles and to study the influence of such charges on the stability of the aqueous dispersions to electrolytes. The influence of interparticulate cohesion in forming a rigid polymeric network in the dispersion was also considered. The electropotentials of the aqueous dispersions were measured, and their stability was determined for various concentrations of electrolytes (NaCl, BaCl2, and AlCl3). The maximum degree of separation (S%) and the time to attain it (tmax) were evaluated. The dispersions generally exhibited electronegative potentials, suggesting that the dispersed particles carried negative charges. Dispersions of concentration <5% w/v were inherently unstable with S% values ≥72% and tmax=4 hour. Dispersions of concentrations as high as 15% w/v were stable with no observable separation even after 24 hour, attributable to mutual repulsion of the disperse particles (due to the surface charges) and possibly to formation of a rigid polymeric network. The test electrolytes were generally ineffective in flocculating these dispersions; S% values were ≤25%, attributable to the formation of a rigid polymeric network.