Effects of organic modification of montmorillonite on the properties of hydroxypropyl di-starch phosphate films prepared by extrusion blowing

Abstract

The knowledge gained from starch-nanocomposite-film research has not been fully applied commercially because of the lack of appropriate industrial processing techniques for nanofillers and starch films. Three organically modified montmorillonites (OMMTs) were prepared using a semidry kneading method. The effects of the OMMTs on the structures and properties of starch nanocomposite films, prepared by extrusion blowing, were investigated. The X-ray diffraction (XRD) analysis results revealed that the OMMTs with various quaternary ammonium salts possessed differing layer structures and d-space values. The results of the XRD and Fourier-transform infrared spectroscopy (FT-IR) showed that the starch-OMMT interaction resulted in a structural change, namely the starch-OMMT films possessed a balanced exfoliated and intercalated nanostructure, while the starch-MMT film possessed an exfoliated nanostructure with non-intercalated montmorillonite (MMT). The results of the solid-state nuclear magnetic resonance (NMR) analysis suggested that the starch-OMMT nanocomposite possessed comparatively large quantities of single-helix structures and micro-ordered amorphous regions. The starch-OMMT films exhibited good tensile strength (TS) (maximum of 6.09 MPa) and water barrier properties (minimum of 3.48 × 10-10 g·m·m-2·s-1·Pa-1). This study indicates that the addition of OMMTs is a promising strategy to improve the properties of starch films.