Physical and mechanical properties of thermoplastic starch/montmorillonite nanocomposite films

Glycerol-plasticized starch/clay nanocomposites films were prepared from potato starch and three different loadings of montmorillonite aqueous suspensions by casting, to study the effect of the nanoclay in the properties of starch. The clay dispersion in the films was analyzed by X-ray diffraction (XRD). It was observed that the 001 diffraction peak of clay was shift to lower angles in the nanocomposites patterns providing strong evidence that the clay nanolayers formed an intercalated structure but not complete exfoliation. An improvement in the thermal resistance of starch with the addition of clay was also observed by means of thermogravimetric analysis (TGA). The water absorbed by the nanocomposites measured in an environment with a 75% of constant relative humidity was reduced by the addition of montmorillonite to the starch. The micro-tensile test was performed on the nanocomposite films showing significant improvement in the Young modulus up to 500% for the nanocomposite containing 5 wt% of clay.