Coupling between flow and structure for a lamellar surfactant phase
The flow-structure relation of lamellar phases is studied using rheometry and cross-polarized microscopy under flow. The equilibrium phases show different defects. Low salinities lead to very viscous, "onion" phases, whereas at high salinity, a low viscosity plane lamellar phase is found. Under shear, the latter shows a sudden transition to a viscoelastic gel, with a texture and viscosity very similar to that of the onions. Gelation occurs after a certain delay time, increasing rapidly with salinity, by the nucleation of onions. This allows one to relate the delay time to the defect energy.
Leon
A
Laboratoire de Physique Statistique de l'ENS 24 rue Lhomond, 75231 Paris CEDEX 05, France.
Bonn
D
Meunier
J
Al-Kahwaji
A
Greffier
O
Kellay
H