Neck propagation in polyethylene

Authors

  • Buckley Crist,

    Corresponding author
    1. Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108
    • Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108
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  • Costas Metaxas

    1. Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108
    Current affiliation:
    1. BP Polymers Americas, 150 W. Warrenville Road, H-1, Naperville, IL 60563
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  • Dedicated to Robert N. Haward on his 90th birthday in recognition of his many contributions to the physics of polymers

Abstract

Intrinsic true stress–true strain response was evaluated at room temperature for three linear polyethylene samples deformed in conventional tensile tests. It was observed that high crystallinity is associated with a low rate of strain hardening that results in a sharp neck and a large drop in nominal stress. The maximum and minimum deformation loads are accounted for by Considère's analysis of neck initiation and stabilization, respectively. Following stabilization, neck propagation occurs at a load or nominal stress that is lower than the yield stress. The jump analysis of Ericksen and Hutchinson/Neale predicts steady state neck propagation stresses that are in very good (ca. 10%) agreement with experiment. Although the jump analysis is done in terms of uniaxial stress, the actual value of the propagation stress is established by the triaxial stress state in the neck shoulders. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2081–2091, 2004

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