Influence of Extensional Stress Overshoot on Crystallization of LDPE

Sara Lindeblad Wingstrand, Martin van Drongelen, Kell Mortensen, Richard S. Graham, Qian Huang, Ole Hassager

    Research output: Contribution to journalArticleAcademicpeer-review

    20 Citations (Scopus)
    1 Downloads (Pure)


    Low-density polyethylene (LDPE) shows a stress overshoot in start-up of strong uniaxial extensional flows of constant rate. It is believed that the overshoot is caused by a contraction of the polymer backbone due to alignment of the long chain branches—the consequence being that the molecular strain of the backbone does not increase monotonically with the global strain of the melt. In this study we investigate the semicrystalline morphology of LDPE quenched before, after, and at the overshoot. We do this by combining filament stretching rheometry with ex-situ X-ray scattering. It is found that the overshoot indeed is reflected in the orientation of the crystalline domains of the quenched filaments. In a broader perspective, we show that the final crystalline morphology is determined by the stress at quench—not the strain at quench. With these findings we confirm that the much debated overshoot has a physical origin. More importantly, we conclude that even for complex architectures like branched systems, the crystalline orientation is determined by the backbone stretch rather than the global stretch of the material.
    Original languageEnglish
    Pages (from-to)1134-1140
    Issue number3
    Publication statusPublished - 2017


    • IR-104155


    Dive into the research topics of 'Influence of Extensional Stress Overshoot on Crystallization of LDPE'. Together they form a unique fingerprint.

    Cite this