Preparation And Properties Of Starch/Organic Montmorilomite Nanocomposite Films

The starch/MMT nanocomposite films by solution casting were prepared from modified starch and enhanced with organically montmorillonites (OMMT) to obtain high performance nanocomposites. Nanostructure of OMMT were determined through X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), hermal Gravimetric Analysis (TGA). The Mechanical property, Scanning electron microscope (SEM), Differential scanning caborimetry (DSC), Water vapor permeability (WVP), transmission electron microscopy (TEM), light transmittanceof films were determined to evaluate the starch/OMMT nanocomposite films. The main results were as follows:1. The effects of modifier type on the physico-chemical properties of OMMT and starch/OMMT nanocomposite filmA perfect intercalation structure was formed between the six quaternary ammonium salts and the natural montmorillonite (Na-MMT), the quaternary ammonium salts with high molecular weight were beneficial to increasing the d-spacing and loaded more mass in the interlayer space, the highest and lowest d-spacings were 3.56 nm for D1821MMT and 1.81 nm for 1231MMT, respectively; with the increase in the molecular size of the quaternary ammonium salts, the starch/OMMT composite films exhibited greatest tensile strength (TS,6.16 MPa), water vapor permeability (WVP,1.80×10-10 g·m/m2·s·Pa), a lower glass transition temperature (Tg,17.1?) and better heat-sealing performance; while the addition of OMMT lowered the light transmittance and obtained a less coarse homogeneous phase. The quaternary ammonium salts with large molecular size, such as 1831?1827 and D1821 were more suitable for the production of starch/OMMT nanocomposite films.2. The effects of quaternary ammonium salts content on the physico-chemical properties of OMMT and starch/OMMT nanocomposite filmWhen the modifier content was 50%, the modification reaction balance; medium content of the modifiers were beneficial to increase the d-spacing of OMMT and form intercalation or peeling nanostructure between starch and OMMT. With modifier increasing from 0% to 70%, the TS and light transmission increasing, WVP decreased starch/OMMT composite film. When the modifier content was 30%, starch/OMMT composite films obtained the best mechanical properties, water resistance and light transmittance properties; the starch/OMMT composite films got good heat-sealing performance.3. The effects of starch type and OMMT type on the physico-chemical properties of starch/OMMT nanocomposite filmOxidized and acetylated starch (OAS) and D1821MMT formed intercalation structure and hydrogen bonding interactions, composite film had a highest tensile strength (TS,5.80 MPa) and light transmission (86.83%); stronger hydrogen bonding interactions also occurred between hydroxypropyl distarch phosphate (HPDSP) and 1827MMT composite film formed peeling nanostructure and obtained the lowest water vapor permeability (WVP,1.30× 10-10 g·m·m-2·s-1·Pa-1); high-oxidized starch (HOS)/1827MMT composite film showed the biggest elongation at break (E,45.68%).Three kinds of high performance starch/clay nanocomposite film were obtained to meet the needs of different food packaging.