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Journal of Materials Science

, Volume 14, Issue 10, pp 2482–2492 | Cite as

Fatigue crack propagation in crystalline polymers: effect of moisture in nylon 66

  • P. E. Bretz
  • R. W. Hertzberg
  • J. A. Manson
Papers

Abstract

As part of a study of the effects of crystallinity on fatigue crack propagation (FCP) behaviour in crystalline polymers, the FCP response of nylon 66 was examined as a function of both stress intensity factor range (ΔK) and water content. It was found that FCP rates were exponential functions of ΔK, as expected. However, the FCP rates at constant ΔK decreased as the water content was increased to about 3%; at saturation (8% water), the FCP rates were higher than that observed in dry specimens. Results were interpreted in terms of the incorporation of tightly bound water up to a maximum of one water molecule per two amide groups (at∼ 2% water), followed by the incorporation of loosely bound water (at saturation). The tightly bound water evidently toughens the polymer, while the loosely bound water has a predominantly weakening effect. Examination of fracture surfaces revealed a transition from terminal unstable crack growth (at water contents up to 3%) to tearing (at saturation). Classical fatigue striations were observed only in the specimens containing 2% water—the first time such striations have been unequivocally identified for any crystalline polymer.

Keywords

Fatigue Crack Growth Rate Fatigue Crack Growth Crack Front Fatigue Crack Propagation 

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References

  1. 1.
    E. H. Andrews, “Fracture in Polymers” (Elsevier, New York, 1968).Google Scholar
  2. 2.
    R. W. Hertzberg, “Deformation and Fracture Mechanics of Engineering Materials” (Wiley, New York, 1976).Google Scholar
  3. 3.
    J. A. Manson andR. W. Hertzberg,Crit. Rev. Macro. Sci. 1 (1973) 433.Google Scholar
  4. 4.
    R. W. Hertzberg, J. A. Manson andM. D. Skibo,Polymer. Eng. Sci. 15 (1975) 252.CrossRefGoogle Scholar
  5. 5.
    M. D. Skibo, R. W. Hertzberg, J. A. Manson andS. L. Kim,J. Mater. Sci. 12 (1977) 531.CrossRefGoogle Scholar
  6. 6.
    S. L. Kim, M. Skibo, J. A. Manson andR. W. Hertzberg,Polymer. Eng. Sci. 17 (1977) 194.CrossRefGoogle Scholar
  7. 7.
    M. D. Skibo, R. W. Hertzberg, J. A. Manson andS. L. Kim,J. Mater. Sci. 12 (1977) 551.CrossRefGoogle Scholar
  8. 8.
    M. D. Skibo, J. Janiszewski, R. W. Hertzberg andJ. A. Manson, Proceedings of the International Conference on Toughening of Plastics, 1978 (Plastics and Rubber Institute, London) paper 25.Google Scholar
  9. 9.
    M. D. Skibo, J. A. Manson, R. W. Hertzberg andE. A. Collins,J. Macromol. Sci.-Phys. B14 (1977) 525.CrossRefGoogle Scholar
  10. 10.
    E. H. Andrews andB. J. Walker,Proc. R. Soc. London A 325 (1971) 57.CrossRefGoogle Scholar
  11. 11.
    N. G. McCrum, B. F. Read andG. Williams, “Anelastic and Dielectric Effects in Polymeric Solids” (Wiley, New York, 1967).Google Scholar
  12. 12.
    Y. S. Papir, S. Kapur, C. E. Rogers andE. Baer,J. Polymer. Sci. 10 (1972) 1305.Google Scholar
  13. 13.
    M. I. Kohan, “Nylon Plastics” (John Wiley & Sons, Inc., New York, 1973).Google Scholar
  14. 14.
    “Zytel” Design Handbook, E. I. duPont de Nemours and Company, 1972.Google Scholar
  15. 15.
    R. Puffr andJ. Sebenda, in “Macromolecular Chemistry, Prague, 1965”, edited by O. Wichferle and B. Sedlvacek (Interscience, New York, 1967) p. 79.Google Scholar
  16. 16.
    D. C. Prevorsek, R. H. Butler andH. Reimschussel,J. Polymer. Sci. A2 9 (1971) 867.CrossRefGoogle Scholar
  17. 17.
    K. H. Illers,Makromol. Chem. 38 (1960) 168.CrossRefGoogle Scholar
  18. 18.
    H. W. Starkweather,J. Macromol. Sci. B3 (1969) 727.CrossRefGoogle Scholar
  19. 19.
    M. D. Skibo, R. W. Hertzberg, andJ. A. Manson, unpublished work on toughened nylon, Lehigh University (1978).Google Scholar
  20. 20.
    R. W. Hertzberg, M. D. Skibo, andJ. A. Manson, ASTM Symposium on Fatigue Mechanisms, Kansas City, 1978 (to be published).Google Scholar
  21. 21.
    R. W. Hertzberg, M. D. Skibo andJ. A. Manson,J. Mater. Sci. 13 (1978) 1038.CrossRefGoogle Scholar
  22. 22.
    A. F. Laghouati, Thesis, 3rd Cycle, Universite de Technologie de Compiegne (1977).Google Scholar
  23. 23.
    M. D. Skibo, R. W. Hertzberg andJ. A. Manson,J. Mater. Sci. 11 (1976) 479.CrossRefGoogle Scholar
  24. 24.
    B. Tomkins andW. D. Biggs,ibid. 4 (1969) 544.CrossRefGoogle Scholar
  25. 25.
    L. J. Broutman andS. K. Gaggar,Int. J. Polymer. Mater. 1 (1972) 295.CrossRefGoogle Scholar
  26. 26.
    W. J. Plumbridge,J. Mater. Sci. 7 (1972) 939.CrossRefGoogle Scholar
  27. 27.
    K. Yamada andM. Suzuki,Kobunhi Kagaku 30 (1973) 206.CrossRefGoogle Scholar
  28. 28.
    A. J. McEvily Jr, R. C. Boettner andT. L. Johnston, in “Fatigue—An Interdisciplinary Approach” (Syracuse University Press, Syracuse, NY, 1964).Google Scholar

Copyright information

© Chapman and Hall Ltd. 1979

Authors and Affiliations

  • P. E. Bretz
    • 1
  • R. W. Hertzberg
    • 1
  • J. A. Manson
    • 1
  1. 1.Materials Research CenterLehigh UniversityBethlehemUSA

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