Novel kinetic effects in viscoelastic surfactant solutions under shear

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:289015

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

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

Using small-angle neutron scattering (SANS), we have investigated the transient alignment and relaxation under Couette shear of viscoelastic aqueous micellar solutions of cetyltrimethylammonium 3,5- dichlorobenzoate (CTA3,5CL) mixtures at concentrations well above {phi}{sup *} (but below 1.0 wt.%). Time constants of the order of tens 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 alignment and relaxation behavior. At low micellar surface charge density ({sigma})(e.g., in pure CTA3,DCl), 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.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 289015
• Report Number(s): CONF-941144--185; ON: DE96013790
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
AQUEOUS SOLUTIONS
COUETTE FLOW
MICELLAR SYSTEMS
NEUTRON DIFFRACTION
NEUTRONS
SHEAR
SMALL ANGLE SCATTERING
SURFACTANTS