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Strain-Induced Crystallization in Rubbers

  • Giuseppe Allegra

Abstract

As it is well known, crosslinked samples of stereoregular polymers are able to crystallize at temperatures higher than T m o , i.e., the ideal melting point, if suitably deformed. Conformational entropy decrease of the molten chains, induced by deformation, is responsible for the effect1, which is especially important in improving the ultimate properties of the material. It is the purpose of the present study i) to clarify the critical aspects of melting in strained rubberlike samples; ii) to discuss the favourable effect induced by relatively small values of the specific melting entropy upon the rubber’s technical performance; iii) to point out the relationship between conformational disorder in polymer crystallites and the small entropic value referred to above, discussing few examples of practical relevance2.

Keywords

Natural Rubber Statistical Segment Ultimate Property Rubberlike Material Stretch Direction 
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.
    P. J. Flory, Thermodynamics of crystallization in high polymers. I. Crystallization induced by stretching, J. Chem. Phys. 15: 397 (1947).ADSCrossRefGoogle Scholar
  2. 2.
    G. Allegra and M. Bruzzone, Effect of entropy on strain-induced crystallization, Macromolecules 16: 1167 (1983).Google Scholar
  3. 3.
    G. Allegra, The angular distribution of crystallinity in a stretched rubberlike polymer; Makromol. Chem. 181:1127 (1980).Google Scholar
  4. 4.
    W. L. Wu, A Thermodynamic approach to the stress-induced crystallization in cross-linked rubbers, J. Polym. Sci. Polym. Phys. Ed. 16:1671 (1978).CrossRefGoogle Scholar
  5. 5.
    K. J. Smith, Jr., Crystallization of stretched networks and associated elasticity, ACS Symp. Ser. 193 (Elastomers Rubber Elasticity): 293 (1982).CrossRefGoogle Scholar
  6. 6.
    D. E. Roberts and L. Mandelkern, Thermodynamics of crystallization in high polymers: natural rubber, J. Am. Chem. Soc. 77: 781 (1955).CrossRefGoogle Scholar
  7. 7.
    M. Berger and D. J. Buckley, Structure effects and related polymer properties in Polybutadiene. I. ?reparation and characterization, J. Polymer Sci. Pt.A•1: 2945 (1963).Google Scholar
  8. 8.
    P. Corradini, Conformation of polymer molecules and entropy of melting, J.Polym. Sci., Polym. Symp. 50: 327 (1975).CrossRefGoogle Scholar
  9. M. Bruzzone, A. Carbonaro and L. Gargani, Crystallizable trans-butadiene-piperylene elastomers, Rubber Chem. Technol. 51:907 (1978).Google Scholar
  10. 10.
    P. Corradini, Chain conformation of the high-temperature polymorph of trans-1,4-polybutadiene, J. Polym. Sci., Part B 7: 211 (1969).CrossRefGoogle Scholar
  11. 11.
    G. Perego and M. Cesari, ENIRICERCHE, S. Donato Milanese (Italy), private communication.Google Scholar
  12. K. J. Smith, Jr., Crystallization of networks under stress, Polym. Eng. Sci. 16:168 (1976).Google Scholar
  13. 13.
    G. Natta, P. Corradini, D.Sianesi and D. Morero, Isomor- phism phenomena in macromolecules, J. Polymer Sci. 51: 527 (1961).ADSCrossRefGoogle Scholar
  14. 14.
    G. Allegra and I. W. Bassi, Isomorphism in synthetic macro-molecular systems, Adv. Polymer Sci. 6: 549 (1969).CrossRefGoogle Scholar
  15. 15.
    B. Wunderlich, Isomorphism, in “Macromolecular Physics. 1. Crystal Structure, Morphology, Defect”, p. 147, Acad. Press, N.Y. (1973).Google Scholar

Copyright information

© Springer Science+Business Media New York 1986

Authors and Affiliations

  • Giuseppe Allegra
    • 1
  1. 1.Dipartimento di Chimica del PolitecnicoMilanoItaly

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