We report on the first time-resolved small-angle neutron scattering (SANS) study of the structural relaxation from a shear-induced aligned state back to the isotropic state in a system of giant wormlike reverse micelles. The micelles are formed by lecithin and small amounts of water in cyclohexane. A liquid sample with the micellar volume fraction φ = 0.3 was exposed to a steady shear of γ̇ = 10 s-1 in a Couette shear cell. This was sufficient to transform the whole sample into an aligned state with the polymer-like micelles preferentially oriented parallel to the velocity direction. After cessation of shear, the sample relaxes back to the equilibrium liquid phase. By time-resolved SANS we could follow the relaxation process, which is characterized by a continuous decrease of the order parameter.
Relaxation of Shear-aligned Wormlike Micelles
ANGELICO, Ruggero;CEGLIE, Andrea;AMBROSONE, Luigi
2002-01-01
Abstract
We report on the first time-resolved small-angle neutron scattering (SANS) study of the structural relaxation from a shear-induced aligned state back to the isotropic state in a system of giant wormlike reverse micelles. The micelles are formed by lecithin and small amounts of water in cyclohexane. A liquid sample with the micellar volume fraction φ = 0.3 was exposed to a steady shear of γ̇ = 10 s-1 in a Couette shear cell. This was sufficient to transform the whole sample into an aligned state with the polymer-like micelles preferentially oriented parallel to the velocity direction. After cessation of shear, the sample relaxes back to the equilibrium liquid phase. By time-resolved SANS we could follow the relaxation process, which is characterized by a continuous decrease of the order parameter.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
