NMR Approach to the Swelling Process of PDMS Networks and Silica-Filled Siloxanes

  • J. P. Cohen-Addad
  • A. Viallat

Abstract

This work deals with the NMR observation of the progressive swelling of siloxane systems. Gels re suiting from covalent crosslinks, on the one hand, and network-like structures formed from silica-filled siloxane, on the other hand, were examined. The transverse magnetization of protons was used to probe the unfolding mechanism of elementary chains. The residual energy of spin—spin interactions governing the magnetization dynamics was found to obey static scaling laws upon variation of the solvent concentration. In calibrated gels, these properties reflect both a packing condition and screening effects due to trapped entanglements, whereas neither any affine property nor a packing condition could account for scaling properties observed in silica-filled siloxane systems.

The spin—lattice relaxation rate was found to be independent of the silica concentration, on the one hand, and of the polymer weight fraction w2 (for w2 < 0·5), on the other hand. These two results were assumed to give evidence for the presence of dynamic screening domains, analogous to those existing in any entangled chain solution.

Keywords

Relaxation Rate Residual Energy Transverse Magnetization Chain Segment Silica Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    de Gennes, P. G., Scaling Concepts in Polymer Physics, Cornell University Press, Ithaca, New York, 1979.Google Scholar
  2. 2.
    Bastide, J., Picot, C. and Candau, S., J. Macromol Sci Phys., 1981, B19, 13.Google Scholar
  3. 3.
    Daoud, M., Bouchaud, E. and Jannink, G., Macromolecules, 1986, 19, 1955.CrossRefGoogle Scholar
  4. 4.
    Cohen-Addad, J. P., J. Physique, 1982, 43, 1509.CrossRefGoogle Scholar
  5. 5.
    Cohen-Addad, J. P., Domard, M., Lorentz, G. and Herz, J., J. Phys., 1984, 45, 575.CrossRefGoogle Scholar
  6. 6.
    Viallat, A., Cohen-Addad, J. P. and Puchelon, A., Polymer, 1986, 27, 843.CrossRefGoogle Scholar
  7. 7.
    Andrew, E. R. and Bersohn, R., J. Chem. Phys., 1950, 18, 159.CrossRefGoogle Scholar
  8. 8.
    Belkebir-Mrani, A., Beinert, G., Herz, J. and Rempp, P., Eur. Polym. J., 1973, 13, 277.CrossRefGoogle Scholar
  9. 9.
    Cohen-Addad, J. P., Roby, C and Sauviat, M., Polymer, 1985, 26, 1231.CrossRefGoogle Scholar
  10. 10.
    Cuniberti, C., J. Polymer Science, Part A2, 1970, 8, 2051.Google Scholar
  11. 11.
    Cohen-Addad, J. P., Viallat, A. and Huchot, P., Macromolecules, 1987, 20, 2146.Google Scholar

Copyright information

© Elsevier Applied Science Publishers Ltd 1988

Authors and Affiliations

  • J. P. Cohen-Addad
    • 1
  • A. Viallat
    • 1
  1. 1.Laboratoire de Spectrométrie Physique associé au CNRSUniversité Scientifique, Technologique et Médicale de GrenobleSt Martin d’Hères CedexFrance

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