Freezing/thawing effects on the exfoliation of montmorillonite in gelatin-based bionanocomposite



Freezing/thawing is used as a new method to elaborate exfoliated gelatin-Montmorillonite (MMT) bionanocomposites. The data of X-ray diffraction and transmission electron microscopy indicate that freezing/thawing is an effective approach to exfoliate the clay for concentrations higher than 5 mass% in gelatin matrix. In addition, after freezing/thawing process to introduce, the crystallinity (triple-helix content) of gelatin-MMT bionanocomposites is improved, revealing that freezing/thawing method has the advantages for gelatin molecules to renature into triple-helix. Specially, the data of Fourier transform infrared indicate that freezing/thawing may be induce more hydrogen bond interactions in gelatin-MMT bionanocomposites due to the better dispersion of MMT. The mechanical measurements and thermogravimetric analysis show that gelatin-MMT bionanocomposites prepared by freezing/thawing display enhanced mechanical properties and thermal stability in comparison with the ones prepared by conventional blending at the same clay content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013