Comparison of the Rheological Behavior of Solutions and Formulated Oil-in-Water Emulsions Containing Carboxymethylcellulose (CMC)

In this study, it was aimed to compare the rheological properties of carboxymethylcellulose (CMC) in aqueous solutions and their corresponding emulsions containing 0.05, 0.1, 0.25, and 0.5% CMC in the aqueous phase. Samples with 0.05 and 0.1% CMC showed Newtonian behavior, but shear-thinning behavior was observed in CMC solutions and emulsions with increasing CMC concentrations to 0.25% and 0.5%. Rheological behavior of all samples were modeled by Power law (R ² = 0.986–197) and Casson models (R ² = 0.968–1). According to the Ostwald–de Waele model, the consistency index of all samples was increased and the flow behavior index decreased with increasing CMC concentration. Comparison of our data with four predicting models (Einstein, Larson, Pal, and Dougherty-Krieger equations) showed that the viscosity of continuous phase controls the viscosity of emulsions with high CMC concentrations and these models are not applicable for such situations. Addition of CMC increased the emulsion stability of O/W emulsions. This stability was increased with increasing CMC concentrations.