Preparation and barrier properties of chitosan-layered silicate nanocomposite films

Abstract

In this study, chitosan nanocomposite films were prepared using a solvent-casting method by incorporation of an organically modified montmorillonite (Cloisite 10A). The effect of filler concentration on the water vapor permeability, oxygen permeability, mechanical and thermal properties of the composite films was evaluated. The structure of nanocomposites and the state of intercalation of the clay were characterized by XRD. The water vapor permeability of pure chitosan films was measured as a function of relative humidity (RH). It was found that the permeability value increased with an increase in RH. The water vapor and gas permeability values of the composite films decreased significantly with increasing filler concentration. Permeation data was fitted to various phenomenological models predicting the permeability of polymer systems filled with nanoclays as a function of clay concentration and aspect ratio of nanoplatelets. According to the XRD results, an increase in basal spacing was obtained with respect to pure clay for chitosan/clay nanocomposites. This demonstrated the formation of intercalated structure of clay in the polymer matrix. Tensile strength and elongation at break of the composites increased significantly with the addition of clay, however the thermal and color properties of the films were not much affected by the intercalation of clay into polymer matrix.