Structural relaxation behavior of strain hardened shape memory polymer fibers for self-healing applications

Authors

  • Pengfei Zhang,

    1. Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, Louisiana
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  • Guoqiang Li

    Corresponding author
    1. Department of Mechanical Engineering, Southern University, Baton Rouge, Louisiana
    • Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, Louisiana
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Correspondence to: G. Li (E-mail: lguoqi1@lsu.edu)

ABSTRACT

In this study, shape-memory polyurethane (SMPU) fibers were strain hardened by cold-drawing programming (CDP) process. The programmed fibers are experimentally studied on the physical and thermomechanical properties. Structural relaxation, which determines shape memory capability of the SMP fibers, is quantified by conformational entropy change. Based on the entanglement tube theory and reptation theory, the entropic force is derived as a “bridge” to link the stress relaxation and structural relaxation, and thus structural relaxation can be evaluated by stress relaxation. It was found that the CDP SMPU fibers would still have good crackclosing capability after 13 years of hibernation in polymer matrix composite. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013, 51, 966–977

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