Cellulose Derivatives As Rheology Modifiers for Cosmetic Applications

Cellulose derivatives are often used in cosmetics industry as rheology modifiers for formulating a large variety of consumer products. Conventionally, the industrial practice is to quantify shear rheology response over a very wide range of shear rates. A well-defined shear thinning behavior is known to provide formulations with high viscosity and additional stability against flocculation or precipitation during storage, and adequate viscosity reduction facilitates mixing and pouring as well as dispensing and drop formation. Even though substantial efforts have focused on the characterization of the shear rheology response of polysaccharide solutions, correlating material properties to processability in operations that involve drop formation and liquid transfer has remained a significant challenge. The missing, critical link in the processability puzzle arises due to unresolved challenges in characterization the macromolecular response to extensional flow, for shear-free extensional flow field gets created spontaneously in freely-draining liquid neck encountered during drop formation and dispensing operations. Using dripping-onto-substrate (DoS) rheometry protocols we developed recently, we characterize the pinch-off dynamics, and extensional rheology of aqueous solutions several cellulose derivatives to elucidate the influence of flexibility, extensibility and charge on the flow behavior and processability.