Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-27T02:10:27.549Z Has data issue: false hasContentIssue false
  • English
  • Français

Shear-Enhanced Structure and Dynamics in Semidilute Polymer Solutions

Published online by Cambridge University Press:  25 February 2011

P. K. Dixon ,
D. J. Pine  and
X.-L. Wu
P. K. Dixon
Affiliation:
Exxon Research and Engineering Co., Annandale, NJ 08801.
D. J. Pine
Affiliation:
Exxon Research and Engineering Co., Annandale, NJ 08801.
X.-L. Wu
Affiliation:
Department of Physics, University of Pittsburgh, Pittsburgh, PA 15260.
Get access

Abstract

We present elastic light scattering measurements of a semidilute polymer solution under shear flow. The basic symmetries observed in the shear-enhanced structure factor agree with the predictions of recently proposed theoretical models. The enhancement appears to be due to a coupling between the polymer concentration and shear flow through the concentration-dependent viscosity and normal stress coefficients. We also found an unexpected long wavelength peak in the shear-enhanced structure factor. Transient scattering measurements upon the cessation of shear have revealed the origin of this peak. The polymer solution demonstrates two modes of relaxation for concentration fluctuations in equilibrium due to a coupling between collective diffusion and stress relaxation. The transient scattering measurements indicate that the mechanism that couples the concentration fluctuations to the shear flow, and thereby enhances concentration fluctuations, selectively enhances only the slower of the two equilibrium modes. This selective enhancement generates the long wavelength peak in the shear-enhanced structure.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 248: Symposium O – Complex Fluids , 1991 , 127
Copyright
Copyright © Materials Research Society 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Strate, G. Ver, Philippoff, W., Polym. Lett. 12, 267 (1974).CrossRefGoogle Scholar
2. Rangel-Nafaile, C., Metzner, A.B., and Wissbrun, K.F., Macromolecules 17, 1187 (1984).Google Scholar
3. Helfand, E. and Fredrickson, G.H., Phys. Rev Lett. 62, 2468 (1989).Google Scholar
4. Onuki, A., Phys. Rev.Lett. 62, 2472 (1989).Google Scholar
5. Onuld, A., J. Phys. Soc. Jap. 59, 3423 (1990).Google Scholar
6. Onuki, A., J. Phys. Soc. Jap. 59, 3427 (1990).CrossRefGoogle Scholar
7. Milner, S. T., Phys. Rev. Lett. 66, 1477 (1991).Google Scholar
8. Doi, M., in Dynamics and Patterns in Complex Fluids: New Aspects of Physics and Chemistry Interfaces, ed. Onuki, A. and Kawasaki, K. (Springer, 1990).Google Scholar
9. Wu, X.-I., Pine, D. J. and Dixon, P. K., Phys. Rev. Lett. 66, 2408 (1991).Google Scholar
10. Hashimoto, T. and Fujioka, K., J. Phys. Soc. Jap. 60, 356 (1991).Google Scholar
11. Yanase, H., Moldenaers, P., Mewis, J., Abetz, V, Egmond, J. van and Fuller, G. C., Rheol. Acta 30, 89 (1991).Google Scholar
12. Milner, S. T., (Private Communication).Google Scholar
13. Dixon, P. K., Pine, D. J. and Wu, X-I., (Preprint).Google Scholar
14. Adam, M. and Delsanti, M., Macromolecules 18, 1760 (1985).Google Scholar
15. Park, J. O. and Berry, G. C., Macromolecules 22, 3022 (1989).Google Scholar
16. Chan, C.K., Perrot, F., Beysens, D., Phys. Rev. Lett. 61, 412 (1988).Google Scholar
17. At low shear rates, the distortion of the equilibrium structure factor due to shear leads to the enhancement of fluctuations for qxqy>O and suppression for qxqy<O. We measure an identical (D in both regions.O+and+suppression+for+qxqyGoogle Scholar
18. Brochard, F. and Gennes, P. G. de, Macromolecules 10, 1157 (1977).CrossRefGoogle Scholar
19. Brochard, F., J. Physique 44, 39 (1983).Google Scholar
20. Brochard, F. and Gennes, P. G. de, PhysicoChemical Hydrodynamics 4, 313 (1983).Google Scholar