Fabrication and characterization of hybrid sodium montmorillonite/TiO2 reinforced cross-linked wheat starch-based nanocomposites.

Abstract

In this work, a novel cross-linked wheat starch (CLWS)-based ternary nanocomposite films with incorporation of sodium montmorillonite (Na-MMT) (3%-7% wt.) and titanium dioxide (TiO2) (1%-4% wt.) nanoparticles were fabricated using casting method. CLWS film exhibited better physical, mechanical and thermal properties compared with the native wheat starch (NWS) film. Incorporation of the nanoparticles into the film solution resulted in a decrease in water vapor permeability (WVP), water solubility (WS), moisture content (MC) of the films, whereas density increased. Nano-TiO2 blocked the UV light effectively and >99% of UV was removed by the film containing 4% TiO2. Affecting by the addition of nanomaterials, the amounts of ultimate tensile strength (UTS) and Young's modulus (YM) values enhanced, while elongation at break (EB) ones diminished. By the Furrier transform infrared (FT-IR) spectroscopy, the creation of new hydrogen bonds between the starch's hydroxyl groups and nanomaterials was confirmed. Formation of a completely exfoliated structure for CLWS/Na-MMT/TiO2 nanocomposites was proved by XRD. SEM micrographs exhibited appropriate dispersion of nanomaterials through the films surface particularly at lower concentrations. The thermogravimetric analysis (TGA) results revealed that the addition of nanomaterials especially TiO2 improved the thermal stability of the nanocomposite films.