Attempt to Explain Crazing in Amorphous Thermoplastics and Adhesion Fractures in Semicrystalline Thermoplastics and Filled Polymers

  • G. Menges

Abstract

In stressed amorphous thermoplastics, cracklike phenomena are observed to develop perpendicularly to the highest normal strain. In semicrystalline thermoplastics, adhesive cracks occur mainly at spherulite boundaries which are positioned perpendicularly to the highest normal strain. Corresponding results were found with multiphase materials, e.g., filled elastomers, thermosets, and thermoplastics.

From the phenomenological similarity of all these observations, the conclusion is drawn that crazes in amorphous thermoplastics are adhesion fractures at particle boundaries. Such particle boundaries are, for instance, the boundaries of raw-material grains which are not destroyed during the plasticizing and processing of a material. Consequently, similar conditions exist as with multiphase materials; the properties of the particles, however, differ less. As “craze material”, “soft” particles must be regarded as those which are stretched during the propagation of the craze.

The surprising existence of constant threshold values of normal strain for the formation of adhesion cracks in all the plastic materials mentioned is explained by the power-law dependence of secondary valence forces (adhesion forces) on distance. After a certain deformation, adhesion cracks develop at numerous places on account of the statistical distribution of critical phase boundaries. This leads to the formation of microcracks. These cracks grow until they reach particles which stop them. These considerations suggest that the strain limit for debonding at critical phase boundaries be estimated by means of an equation which is based on Griffith’s theory and solved with respect to strain. Also, an attempt is made to explain the dependence of strain at fracture on strain rate.

Keywords

Phase Boundary Filler Particle Strain Limit Particle Boundary Multiphase Material 
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.
    Kambour, R. P., Polymer Eng. Sci., 8 (4), 281–289 (1968).CrossRefGoogle Scholar
  2. 2.
    Morbitzer u. Holm, unpublished work of Farbenfabriken Bayer Leverkusen (1972).Google Scholar
  3. 3.
    Menges, G., and Schmidt, H., Kunststoffe, 57 (11), 885–890 (1967).Google Scholar
  4. 4.
    Menges, G., “Erleichtertes Verständnis des Werkstoffverhaltens bei verformungsbezogener Betrachtungsweise”, Fortschrittsbericht VDI-Z,Series 5, No. 12.Google Scholar
  5. 5.
    Schmidt, H., “Untersuchungen der Fließzonenbildung und des mechanischen Langzeitverhaltens von thermoplastischen Kunststoffen bei ein-und zweiachsig wirkenden Zugspannungen”, Thesis RWTH, Aachen (1971).Google Scholar
  6. 6.
    Menges, G., Dolfen, E., Papers of Haus der Technik H 159, Essen, 1967.Google Scholar
  7. 7.
    Dolfen, E., “Bemessungsgrundlagen für tragende Bauelemente aus glasfaserverstärkten Kunststoffen, insbesondere durch Glasseidenmatten bewehrte Polyesterharze”, Thesis RWTH, Aachen (1969).Google Scholar
  8. 8.
    Menges, G., Alf, E., Kunststoffe, 62 (4), 259–267 (1972).Google Scholar
  9. 9.
    Menges, G., Riess, R., and Taprogge, R., Paper read at the Sixth Kunststofftechnisches Kolloquium of the IKV, Aachen, West Germany, 1972, Institut für Kunststoffverarbeitung; see also Materialprüfung, 14 (4), 141–146 (1972).Google Scholar
  10. 10.
    Menges, G., Schmidt, H., and Berg, H., Kunststoffe, 60 (11), 868–872 (1970).Google Scholar
  11. 11.
    Roberg, P., “Dimensionierungsgrundlagen für dynamisch beanspruchte Kunststoff-Rohrsysteme, dargestellt am Beispiel einer PVC-hart-Rohrleitung”, Thesis RWTH, Aachen (1971).Google Scholar
  12. 12.
    Alf, E., Thesis RWTH, Aachen (1972).Google Scholar
  13. 13.
    Menges, G., and Roskothen, H.-J., Kunststoff-Rundschau, No. 9, 479–487 (1972).Google Scholar
  14. 14.
    Bonart, R., Kolloid-Z. u. Z. Polymere, 231 (1–2), 438–456 (1969).Google Scholar
  15. 15.
    Schwarzl, F. R., Kunststoff-Rundschau, 18 (1), 49–55 (1971).Google Scholar
  16. 16.
    Hattori, T., Tanaka, K., and Matsuo, M., Polymer Eng. Sci.,12 (3), 119–203 (May 1972). (cf. for further literature).Google Scholar
  17. 17.
    Pohl, E., Gruber, T., and Taeger, F., Plaste und Kautschuk, 19 (3), 438 (1972).Google Scholar
  18. 18.
    Szabo, C., Grundlagen einer neuen Festigkeitstheorie, Vols 1 and 2, Bauverlag GmbH, Wiesbaden and Berlin, Germany (1971).Google Scholar

Copyright information

© Springer Science+Business Media New York 1973

Authors and Affiliations

  • G. Menges
    • 1
  1. 1.Institut für KunststoffverarbeitungAachenWest Germany

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