Glycerol/starch/Na+-montmorillonite nanocomposites: A XRD, FTIR, DSC and 1H NMR study

We studied the influence of glycerol/MMT loading on the nanocomposites morphology prepared from amylose starch biopolymer with various glycerol/MMT (Na+-montmorillonite) concentrations. Samples were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and proton nuclear magnetic resonance (H-1 NMR) measurements. XRD results highlighted the impact of glycerol on the MMT exfoliation: with 15% glycerol imposed the largest inter-lamella spacing (d-spacing) value. Newly formed hydrogen bonds and the interaction among starch/glycerol/MMT were evidenced by peaks associated with -OH stretching located at 3300 cm(-1) and 999 cm(-1) from the FTIR spectra. DSC measurements revealed that glass transition temperature (T-g) decreased with increasing glycerol content. MMT also lowered the crystallization temperature (T-m) and suppressed the overall sample crystallinity. Proton NMR spectra obtained at 25 degrees C and 70 degrees C from samples containing only starch and glycerol provided important clues for explaining the starch and glycerol interaction. (C) 2010 Elsevier Ltd. All rights reserved.