Abstract
This paper examines the initiation of necking in a metallocene-catalyzed high-density polyethylene. When the specimen is uniaxially deformed, the necking is usually initiated between the first and second yield points, and the neck is stabilized at the second yield point. The initiation of necking was explained by a first-order catastrophic phase transition analogous to the model of a van der Waals gas. At the first yield point, the stacked lamellar clusters are fragmented into cubic cluster units of single chain size; the rearrangement of these units under uniaxial tension produces the texture of necking. Catastrophic arrangement of the cluster units results in a sudden emergence of a locally close-packed layer structure. This is the precursor of necking, and several layered plates are stabilized at the second yield point. The layered plate collapses via sliding of the cubic units by means of the interchain links, to form macroscopic neck; the plate thus behaves as a unit for the necking process. The continual collapse from one plate to another corresponds to the neck propagation.
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Nitta, Kh., Kuriyagawa, M. Application of catastrophe theory to neck initiation of metallocene-catalyzed high-density polyethylene. Polym J 44, 245–251 (2012). https://doi.org/10.1038/pj.2011.119
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DOI: https://doi.org/10.1038/pj.2011.119
