CHANGE IN THE 2-STEP FLOW BEHAVIOR ON AGING THE TERNARY MIXTURE COMPRISING MONOALKYL CATIONIC SURFACTANT, LONG-CHAIN ALCOHOL AND WATER - II- ANALYSIS OF THE CREEP-BEHAVIOR

A two-step development of the internal structure on aging the ternary mixture comprising cetyltrimethylammonium chloride (C(16)CA), cetyl al cohol (C16OH), and water was elucidated from the change in the creep b ehavior. The system was expressed by a six-element model comprising tw o Voigt units in series with a Maxwell unit. A similar increase in the instantaneous elastic modulus G(o), the Newtonian viscosity eta(o), a nd the elastic modulus and viscosity of the Voigt units (G(1), eta(1)) with a longer retardation time tau(1) were observed on aging up to 1- 3 days, followed by a leveling off. Conversely, the elastic modulus an d viscosity of the Voigt units (G(2), eta(2)) with a shorter retardati on time tau(2) were constant at the beginning, followed by an increase on aging. From a cryo-SEM observation, we confirm that the two-step d evelopment considered from the creep properties on aging was caused by an initial coagulation to form a network of multilamellar vesicles, a nd a subsequent phase transition from vesicles to lamellae. (C) 1998 E lsevier Science B.V.