The role of the interphase on the chain mobility and melting of semi-crystalline polymers : a study on polyethylenes

S. Rastogi, D.R. Lippits, A.E. Terry, P.J. Lemstra

    Research output: Chapter in Book/Report/Conference proceedingChapterAcademic

    11 Citations (Scopus)

    Abstract

    In semi-cryst. polymers, a range of morphologies can be obtained in which a chain may traverse the amorphous region between the crystals or fold back into the crystals leading to adjacent or non-adjacent re-entry, depending on the mol. architecture and crystn. conditions. This causes topol. variations on the crystal surface and the occurrence of an interphase between the cryst. and amorphous domains, thus affecting the mech. properties. In this chapter, we will discuss how the morphol. within the interphase plays a prominent role in drawability, lamellar thickening and melting of thus crystd. samples. Normally, for linear polymers it is anticipated that extended chain crystals are thermodynamically most favorable, and ultimately, taking the example of linear polyethylene, it is shown that such chains would form extended chain crystals. However, this condition will not be realized in a range of polymers upon crystn. from the melt, such as those which do not show lamellar thickening or in branched polymers where the side branches cannot be incorporated within the crystal and hence fully extended chains are not possible. Prom a series of expts., it is shown that with sufficient time and chain mobility, although extended chain crystals are not achievable, the chains still disentangle and a thermodynamically stable morphol. is formed with a disentangled crystallizable interphase. The disentangled interphase has implications in the melting behavior of polymer crystals. It is feasible to melt these crystals by simple consecutive detachment of chain segments from the cryst. substrate. Clear distinction in different melting processes is obsd., by the differences in the activation energies required for the consecutive detachment of chain segments or clusters of chain segments. The differences in the melting behavior, revealed during different heating rates, have consequences on the chain dynamics. [on SciFinder (R)]
    Original languageEnglish
    Title of host publicationProgress in understanding of polymer crystallization
    EditorsG. Reiter, G.R. Strobl
    Place of PublicationBerlin
    PublisherSpringer
    Pages285-327
    ISBN (Print)978-3-540-47305-3
    DOIs
    Publication statusPublished - 2007

    Publication series

    NameLecture Notes in Physics
    Volume714
    ISSN (Print)0075-8450

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