The Rheology of Aqueous Solutions of Ethyl Hydroxy-Ethyl Cellulose (EHEC) and its Hydrophobically Modified Analogue (hmEHEC) II: Extensional Flow Response in Capillary Break-up, Jetting and in a Cross-Slot Extensional Rheometer

Cellulose derivatives containing associating hydrophobic groups along their hydrophilic backbone are used as rheology modifiers in the formulation of water-based spray paints, medicinal sprays, cosmetics and printable inks. Jetting and spraying applications of these materials involve progressive thinning and break-up of a fluid column or sheet into drops. Strong extensional kinematics develop in the thinning fluid neck. In viscous Newtonian fluids, inertial and viscous stresses oppose the surface tension-driven instability. In aqueous solutions of polymers such as Ethyl Hydroxy-Ethyl Cellulose (EHEC), chain elongation provides additional elastic stresses that can delay the capillary-driven pinch-off, influencing the sprayability or jettability of the complex fluid. In this study, we quantify the transient response of thinning Page 3 of 52 Soft Matter