Characterization of Montmorillonites by Infrared and Raman Spectroscopy for Preparation of Polymer-Clay Nanocomposites.

The detailed structural chemistry of clay minerals is an important aspect of polymer-clay nanocomposite research. A variety of analytical methods are currently available for material characterization. Keep in mind, however, that each method has some limitations. The best results are usually achieved by a combination of several analytical methods. The contribution demonstrates the potential and applicability of infrared and Raman spectroscopy in identification and structural characterization of montmorillonites. The vibrational spectra of montmorillonites (SAz-2, STx-1, SWy-2 and Kunipia-F), obtained by Fourier Transform infrared spectroscopy in the near infrared region (8000-4000 cm-1 ) and in the middle infrared region (4000-400 cm-1 ) together with Fourier Transform Raman measurements in the region from 4000-50 cm-1 , are presented. The aim of the experimental study was to compare the spectral data of both analytical techniques in terms of their sensitivity to chemical composition, isomorphic substitution of central atoms, and layer stacking order of the clay minerals. The results confirmed that Fourier Transform infrared spectroscopy through middle infrared and near infrared spectral regions provided the most comprehensive information about octahedral, tetrahedral and hydroxyl structure units of montmorillonites.