Structure and dynamic mechanical properties of melt intercalated polyamide 6 - Montmorillonite nanocomposites

Arthur N. Wilkinson, Zakaria Man, John L. Stanford, Petri Matikainen, Mark L. Clemens, Graham C. Lees, Christopher M. Liauw

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Polymer-layered silicate nanocomposites (PLSN), based on polyamide 6 (PA6) and montmorillonite (MMT) modified with an octadecylammonium salt, were produced via melt compounding in a co-rotating twin-screw extruder. Wide angle X-ray diffraction (WAXD) and TEM revealed a PLSN containing 3.3% by weight (wt.-%) of MMT to exhibit a mixed exfoliated/intercalated morphology, consisting mainly of individual silicate lamellae together with some intercalated stacks, resulting in a mean value of 1.8 lamellae per particle. In contrast, a PLSN containing a higher level of 7.2 wt-% MMT exhibited a more ordered intercalated structure, consisting mainly of a distribution of lamellae stacks with a mean value of 3.8 lamellae per particle. The dispersion of MMT in the PLSN generated very large polymer-filler interfacial areas, resulting in significant increase in the volume of constrained PA6 chain segments. Consequently, significant changes in the ratio of α/γ crystallites and in the thermal behaviour of the matrix PA6 were observed during WAXD, DSC and dynamic-mechanical thermal analysis (DMTA) studies of the PLSN. In particular, damping data from DMTA showed relaxations between Tg and Tm resulting from amorphous polymer chain segments constrained at the polymer-filler interface, indicating the formation of a continuous phase of constrained polymer. In contrast, a PA6 microcomposite formed using unmodified MMT generated much lower polymer-filler interfacial area, with most of the MMT residing within large, poorly wetted aggregates. Consequently, changes to the thermal behaviour of the matrix PA6 were much less significant than those induced in the PLSN. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.
    Original languageEnglish
    Pages (from-to)917-928
    Number of pages11
    JournalMacromolecular Materials and Engineering
    Volume291
    Issue number8
    DOIs
    Publication statusPublished - 7 Aug 2006

    Keywords

    • Morphology
    • Nanocomposites
    • Organoclay
    • Polyamides

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