Stretching Flows

  • F. N. Cogswell


Polymer melts resist flow. In viscous flow the energy producing the flow is dissipated as heat. During flow some energy may be stored, giving rise to elastic effects, and, should the stress exceed some critical value, fracture may occur. When we are considering simple fluids then the viscosity may be clearly defined. The earlier chapters have shown that the viscosity of a polymer melt depends strongly on temperature, pressure and rate of deformation. This chapter introduces one further variable: geometry.


Draw Ratio Dead Zone Melt Flow Index Deborah Number Extrusion Pressure 
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  1. 1.
    F. Trouton, Proc. Roy. Soc. A77, 426–40 (1906).Google Scholar
  2. 2.
    A. S. Lodge, Elastic Liquids, Academic Press, 114-18 (1964).Google Scholar


  1. 1.
    J. Dealy, Poly. Eng. Sci., 11, 433–45 (1971). (General review of both theory and practice in stretching flows.)CrossRefGoogle Scholar
  2. 2.
    F. N. Cogswell, Trans. Soc. Rheol., 16, 3, 383. (A review of rheometers for studying stretching flows.)Google Scholar
  3. 3.
    F. N. Cogswell, Appl. Poly. Symp., 27, 1–18 (1975). (A survey of rheological experiences with extensional flows.)Google Scholar
  4. 4.
    H. M. Laun and H. Munstedt, Rheol. Acta, 15, 10, 517–24 (1976). (Probably the most detailed study of the stretching flow response of a single melt.)CrossRefGoogle Scholar

Copyright information

© Applied Science Publishers Ltd 1978

Authors and Affiliations

  • F. N. Cogswell
    • 1
  1. 1.Plastics DivisionImperial Chemical Industries LimitedWelwyn Garden City, HertsUK

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