Rheological Properties of Highly Dilute Viscoelastic Aqueous Detergent Solutions

Abstract

Highly dilute aqueous solutions containing 0.2–0.3 mmol dm⁻³ (80–120 p.p.m.) of some cationic detergents show visible elastic recoil at 25^ÛC¹ although the viscosity of the solutions is as low as 0.9–1.0 mPa s². Some of the rheological properties of aqueous solutions of one of the detergents (cetyltrimethylammonium salicylate (CTA-Sal)) have been studied^{3, 4}. At concentrations between 0.3 and 1.0 mmol dm⁻³ CTA-Sal the solutions behave like ordinary Newtonian solutions at suitably low shear rates, whereas at higher shear rates the solutions show rheopectic behaviour as illustrated in fig. 1.⁴