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Time-dependence of the tensile stiffness and anisotropy of a reinforced thermoplastic

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The stiffening in tension of injection-moulded polypropylene with the addition of glass fibres or spheres was found to depend on strain, time and the direction relative to that of the melt flow, as well as on the percentage and aspect ratio of the glass inclusions. Under loading of long duration this stiffening, expressed in terms of the stiffness factor, increased with time for fibre-filled material but varied little for the sphere-filled. In the latter case, the tensile creep could be predicted with some accuracy by a simple model. The anisotropy of the fibre-filled polypropylene was not time-dependent and conformed to the theory of orthotropic materials.

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  1. 1.

    W. Dawson and B. S. Dyer, “Reinforced Thermoplastics”, Third International Reinforced Plastics Conference (British Plastics Federation, London, 1962).

  2. 2.

    O. R. Strauch, “Use of Solid Glass Spheres in Thermoplastic Polymers”, Reinforced Thermoplastics Conference (Society of Plastics Engineers, Western New England Section, October 1969).

  3. 3.

    L. C. Cessna, B. J. Thomson and R. D. Hanna, S.P.E. J. 25 (10) (1969) 35.

  4. 4.

    S. Turner, Appl. Mater. Res. 4 (1965) 10.

  5. 5.

    R. M. Ogorkiewicz and S. Turner, Plastics and Polymers 39 (1971) 209.

  6. 6.

    R. M. Ogorkiewicz and G. W. Weidmann, J. Mech. Eng. Sci. (to be published).

  7. 7.

    R. M. Ogorkiewicz, Composites 2 (1971) 29.

  8. 8.

    Idem, ibid 3 (1972) 230.

  9. 9.

    R. M. Ogorkiewicz and G. W. Weidmann, Plastics and Polymers 40 (1972) 337.

  10. 10.

    S. Turner, “Creep Studies on Plastics”, Symposium on Mechanical Performance and Design in Polymers, Melbourne, 1970, Applied Polymer Symposia, Vol. 17 (Wiley-Interscience, New York, 1971).

  11. 11.

    ASTM Standard D-638-67T, ASTM Standards, Part 27, “Plastics” (American Society of Testing and Materials, Philadelphia, Pa., 1968).

  12. 12.

    W. S. Mills and S. Turner, “Tensile Creep Testing of Plastics”, Symposium on Developments in Materials Testing Machines (I.Mech.E., London, 1965).

  13. 13.

    J. Dimmock and C. E. Spedding, Composites 1 (1970) 356.

  14. 14.

    J. Dimmock, M.Sc.(Eng.) Thesis, University of London (1968).

  15. 15.

    D. A. Thomas and S. Turner, “Experimental Techniques in Uniaxial Tensile Creep Testing” in “Testing of Polymers”, Vol. 4 (edited by W. E. Brown) (Wiley, New York, 1969).

  16. 16.

    BS 4618, British Standards Institution (1970).

  17. 17.

    S. Turner, Trans. J. Plast. Inst. 31 (1963) 60.

  18. 18.

    S. Turner and R. M. Ogorkiewicz, “Deformational Characteristics of Fibre Reinforced Thermoplastics”, Seventh International Reinforced Plastics Conference (British Plastics Federation, Brighton, 1970).

  19. 19.

    J. H. Davis, “The Reinforcement of Thermoplastic Matrices with Fibres”, Sixth International Reinforced Plastics Conference (British Plastics Federation, London, 1968).

  20. 20.

    R. F. S. Hearmon, “An Introduction to Applied Anisotropic Elasticity” (Oxford University Press, London, 1961).

  21. 21.

    R. M. Ogorkiewicz, J. Mech. Engng Sci. 15 (1973) 102.

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Weidmann, G.W., Ogorkiewicz, R.M. Time-dependence of the tensile stiffness and anisotropy of a reinforced thermoplastic. J Mater Sci 9, 193–200 (1974). https://doi.org/10.1007/BF00550941

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  • Polymer
  • Anisotropy
  • Aspect Ratio
  • Polypropylene
  • Simple Model