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Novel Kinetic Effects in Vkcoelasttc Surfactant Solutions Under Shear

Published online by Cambridge University Press:  22 February 2011

P.D. Butler ,
L.J. Magid ,
P.J. Kreke ,
J.B. Hayter ,
W.A. Hamilton  and
B. Hammouda
P.D. Butler
Affiliation:
University of Tennessee, Department of Chemistry, Knoxville, TN 37996
L.J. Magid
Affiliation:
University of Tennessee, Department of Chemistry, Knoxville, TN 37996
P.J. Kreke
Affiliation:
University of Tennessee, Department of Chemistry, Knoxville, TN 37996
J.B. Hayter
Affiliation:
University of Tennessee, Department of Chemistry, Knoxville, TN 37996
W.A. Hamilton
Affiliation:
University of Tennessee, Department of Chemistry, Knoxville, TN 37996
B. Hammouda
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN 37831
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Abstract

Using small-angle neutron scattering (SANS), we have investigated the transient alignment and relaxation under Couette shear of viscoelastic aqueous micellar solutions of cetyltrimethylarmmonium 3,5-dichlorobenzoate (CTA3,5C1) and CTA3,5C1/CTAB mixtures at concentrations well above ф* (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 (σ) (e.g., in pure CTA3,5C1), the first observation of alignment proceeding in two stages has been made. Increasing a 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.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 376: Symposium BB – Neutron Scattering in Materials Science , 1994 , 309
Copyright
Copyright © Materials Research Society 1995

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References

REFERENCES

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