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Journal of Materials Science

, Volume 5, Issue 11, pp 925–932 | Cite as

Hypothetical mechanism of crazing in glassy plastics

  • A. N. Gent
Papers

Abstract

Crazing in glassy plastics is attributed to a stress-activated devitrification of a small amount of material at the tip of a chance nick or flaw, to a softer rubbery state. Subsequent cavitation of the softened material is then assumed to take place under the action of the same dilatant stress responsible for its formation. A transition to ductile yielding is proposed to occur when the material in the tip region undergoes large deformations before softening.

The proposed mechanism of crazing is shown to provide quantitative predictions for the magnitude of tensile stress at which crazing occurs, the increase in crazing stress with hydrostatic pressure, the transition at high pressures to a yielding process without crazing, the reduction in crazing stress in the presence of certain liquids and vapours and, to some extent, for the effects of temperature and pre-orientation. These theoretical predictions are found to be in reasonably satisfactory agreement with experiment. In view of the limited number of adjustable parameters in the theory (the principal one being the stress-magnification factor associated with a typical nick or flaw), this general agreement over a wide range of experimental conditions and variables suggests that the proposed mechanism of stress-crazing is basically correct.

Keywords

Polymer High Pressure Cavitation Tensile Stress Hydrostatic Pressure 
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.
    B. Maxwell andL. F. Rahm,Ind. Eng. Chem. 41 (1949) 1988.Google Scholar
  2. 2.
    C. C. Hsiao andJ. A. Sauer,J. Appl. Phys. 21 (1950) 1071.Google Scholar
  3. 3.
    O. K. Spurr, Jr, andW. D. Niegisch,J. Appl. Polymer Sci. 6 (1962) 585.Google Scholar
  4. 4.
    R. P. Kambour,Polymer 5 (1964) 143.Google Scholar
  5. 5.
    Idem, J. Polymer Sci. A2 (1964) 4159.Google Scholar
  6. 6.
    B. Biglione, E. Baer, andS. V. Radcliffe, “Fracture 1969: Proceedings of the Second International Conference on Fracture, Brighton, April 1969” (Chapman and Hall, London, 1969) p. 503.Google Scholar
  7. 7.
    D. R. Mears, andK. D. Pae,Polymer Letters 7 (1969) 349.Google Scholar
  8. 8.
    R. N. Haward, B. M. Murphy, andE. F. T. White, “Fracture 1969: Proceedings of the Second International Conference on Fracture, Brighton, April 1969” (Chapman and Hall, London, 1969) p. 519.Google Scholar
  9. 9.
    S. S. Sternstein andL. Ongchin, A.C.S. Polymer Preprints (Sept. 1969).Google Scholar
  10. 10.
    E. E. Ziegler,SPE Journal 10 (4) (1954) 12.Google Scholar
  11. 11.
    I. Wolock andD. George,ibid 12 (2) (1956) 20.Google Scholar
  12. 12.
    E. H. Andrews andL. Bevan, “Physical Basis of Yield and Fracture” (Institute of Physics & Physical Society, London 1967) p. 209.Google Scholar
  13. 13.
    G. A. Bernier andR. P. Kambour,Macromolecules 1 (1968) 393.Google Scholar
  14. 14.
    E. F. T. White, B. M. Murphy, andR. N. Haward,J. Polymer Sci. Part B7 (1969) 157.Google Scholar
  15. 15.
    A. C. Knight,ibid, Part A3 (1965) 1845.Google Scholar
  16. 16.
    J. D. Ferry andR. A. Stratton,Kolloid Z. 171 (1960) 107.Google Scholar
  17. 17.
    S. Newman andS. Strella,J. Appl. Polymer Sci. 9 (1965) 2297.Google Scholar
  18. 18.
    M. H. Litt andA. V. Tobolsky,J. Macromolecular Sci. B1 (1967) 433.Google Scholar
  19. 19.
    K. C. Rusch andR. H. Beck, Jr,ibid B3 (1969) 365.Google Scholar
  20. 20.
    C. E. Inglis,Trans. Instn. Naval Archit. 55 (1913) 219.Google Scholar
  21. 21.
    A. E. H. Love, “A Treatise on the Mathematical Theory of Elasticity”, 4th ed. (Cambridge University Press, London 1927).Google Scholar
  22. 22.
    M. S. Paterson,J. Appl. Phys. 35 (1964) 176.Google Scholar
  23. 23.
    J. D. Ferry, “Viscoelastic Properties of Polymers” (John Wiley and Sons, New York, 1961).Google Scholar
  24. 24.
    E. Passaglia andG. M. Martin,J. Res. Nat. Bur. Standards 68A (1964) 273.Google Scholar
  25. 25.
    A. N. Gent, andP. B. Lindley,Proc. Roy. Soc. (London) A249 (1958) 195.Google Scholar
  26. 26.
    A. N. Gent andD. A. Tompkins,J. Polymer Sci., Part A-27 (1969) 1483.Google Scholar
  27. 27.
    C. W. Stewart,ibid, Part A-28 (1970) 937.Google Scholar
  28. 28.
    A. N. Gent, andD. A. Tompkins,J. Appl. Phys. 40 (1969) 2520.Google Scholar
  29. 29.
    F. Bueche, “Physical Properties of Polymers” (Interscience, New York, 1962).Google Scholar
  30. 30.
    L. R. G. Treloar, “Physics of Rubber Elasticity”, 2nd. ed. (Oxford University Press, London, 1958) chap. 7.Google Scholar
  31. 31.
    E. H. Andrews andL. Bevan, Private communication.Google Scholar
  32. 32.
    D. W. Hadley, P. R. Pinnock andI. M. Ward,J. Mater. Sci. 4 (1969) 152.Google Scholar
  33. 33.
    C. Bridle, A. Buckley, andJ. Scanlan,ibid 3 (1968) 622.Google Scholar
  34. 34.
    M. W. Darlington andD. W. Saunders,J. Phys. D: Appl. Phys. 3 (1970) 535.Google Scholar
  35. 35.
    D. Hull, Private communication.Google Scholar
  36. 36.
    F. A. Mcclintock,J. Appl. Mech. 35 (1968) 363.Google Scholar
  37. 37.
    J. R. Rice andD. M. Tracey,J. Mech. Phys. Solids 17 (1969) 201.Google Scholar
  38. 38.
    K. C. Rusch,J. Macromol. Sci. B2 (2) (1969) 179.Google Scholar
  39. 39.
    S. S. Sternstein, L. Ongchin, andA. Silverman Appl. Polymer Symposia, No. 7. (1968) 175.Google Scholar

Copyright information

© Chapman and Hall Ltd. 1970

Authors and Affiliations

  • A. N. Gent
    • 1
  1. 1.Department of Materials, Queen Mary CollegeUniversity of LondonUK

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