Characterization of polymer-layered silicate (clay) nanocomposites by transmission electron microscopy and X-ray diffraction: A comparative study

Authors

  • Alexander B. Morgan,

    Corresponding author
    1. Fire Science Division, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
    • Inorganic Materials Group, Corporate R&D, The Dow Chemical Company, Midland, MI 48674
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  • Jeffrey W. Gilman

    1. Fire Science Division, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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  • This article is a US Government work and, as such, is in the public domain in the United States of America.

  • Certain commercial equipment, instruments, materials, and companies are identified in this article to adequately specify the experimental procedure. This in no way implies endorsement or recommendation by the National Institute of Standards and Technology.

Abstract

Several polymer-layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide-angle X-ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene-g-maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d-spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand-alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003

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