Novel kinetic effects in viscoelastic surfactant solutions under shear

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:225272

Butler, P D; Magid, L J; Kreke, P J ^[1]; Hayter, J B; Hamilton, W A ^[2]; Hammouda, B ^[3]

---

1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry
2. Oak Ridge National Lab., TN (United States). Solid State Div.
3. National Inst. of Standards and Technology, Gaithersburg, MD (United States)

Using small-angle neutron scattering (SANS), the authors have investigated the transient alignment and relaxation under Couette shear of viscoelastic aqueous micellar solutions of cetyltrimethylammonium 3,5-dichlorobenzoate (CTA3,5Cl) and CTA3,5Cl/CTAB mixtures at concentrations well above {phi}* (but below 1.0 wt.%). Time constants of the order of ten`s of minutes are reported for alignment and relaxation, orders of magnitude slower than any previously observed in similar micellar systems. The collective properties of the network of entangled, threadlike micelles, rather than the individual micellar segments, dominate the alignment and relaxation behavior. At low micellar surface charge density ({sigma}) (e.g., in pure CTA3,5Cl), the first observation of alignment proceeding in two stages has been made. Increasing {sigma} decreases by an order of magnitude the shear rate required to reach full alignment and provides a comparable decrease in the rate constant for relaxation after cessation of shear.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 225272
• Report Number(s): CONF-941144--; ISBN 1-55899-278-2
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DIAGNOSTIC TECHNIQUES
EXPERIMENTAL DATA
MICELLAR SYSTEMS
MICROSTRUCTURE
NEUTRONS
ORDER PARAMETERS
SMALL ANGLE SCATTERING