(1d) In Search of Optimal Mixing Conditions for Rheology Modifiers in Agitated Tanks

Rheology modifiers are ubiquitous in the chemical, food, pharmaceuticals, construction, and cosmetic industries. They are used to enhance stability, viscosity, texture and spreadability across various industries for a wide range of formulations. The effectiveness of rheology modifiers in delivering the target rheology and desired function depends on several factors including the concentration, ionic conditions, and mixing environment in the dispersion medium in the mixing tank. In a mixing tank, the placement of impeller relative to rheology modifier location is critical for process success due to non-uniform shear rate distribution. In some cases, too low of a shear rate environment can cause incomplete activation of rheology modifier resulting in unpredictably long equilibrium times for desired function. In other cases, high shear rate environment can lead to reduced interactions between the rheology modifier and dispersion medium. This work utilizes a hybrid computational and experimental approach to investigate the changes in flow-behavior of dispersion medium with rheology modifier concentration and effectiveness of rheology modifiers in providing a desired rheology as a function of mixing parameters such as shear rate, energy dissipation rate, and impeller intensity in an agitated tank. Overall, it is demonstrated that it is critical to control the local mixing environment for achieving optimal rheology in formulations.