Preparation And Properties Of Starch-clay Nanocomposite Films

In this research, the composite films by extrusion blowing were prepared fromhydroxypropyl distarch phosphate （HPDSP） and enhanced with organically modified clays.The Mechanical property, Permeability, Transparency, Colour and Thermal stability of filmswere determined to evaluate the film. Nanostructure, Molecular force and Micro morphologyof films were determined through X-ray diffraction （XRD）, transmission electron microscopy（TEM）, Fourier Transform Infrared Spectroscopy （FTIR）, Scanning electron microscope（SEM）, Differential scanning caborimetry （DSC） and Thermal Gravimetric Analysis （TGA）.The main results were as follows:1、With the addition of organically modified clays with different hydrophilic properties,significantly greater tensile strength and lower water vapor permeability were obtained.Tensile strength of starch-DK3film increased to2.47MPa, while water vapor permeabilitydecreased to4.31×10^-10g.m/m².s.Pa. XRD and TEM showed starch entered the silicate layersand formed intercalated starch-clay nanocomposite. FTIR showed that clays inhibited theplastication between starch and glycerol to some extent. DSC showed that the intermolecularattraction of thermoplastic starch matrix seemed to be interrupted by the charged clays. Andsubsequently the film backbone chains gained additional segmental mobility which led to thedecrease of Tg.. SEM indicated starch had a more homogeneous phase, with the addition ofclays. It turned out that DK3which had a medium hydrophilic property was more efficient instarch films preparation than other clays due to its good compatibility with HPDSP.2、With DK3content increased from0to15%, significantly greater tensile strength（3.37MPa） and lower water vapor permeability (4.31×10^-10g.m/m².s.Pa) were obtained. Thecolor of films tended to be yellowish. With the increase of DK3from0to15%, thetemperature of50%weight loss of the films increased. XRD showed that DK3concentrationhad little effect on the peak position. FTIR showed that DK3inhibited the plasticationbetween starch and glycerol more markedly, with the increase of DK3from0to15%. XRDand FTIR also indicated that higher glycerol content could inhibit the interaction betweenstarch and DK3. 3、Sugars （glucose, fructose and sucrose） were good plasticizers which improved filmflexibility （E:142%） and caused a reduction in barrier (WVP up to4.78×10^-10g.m/m².s.Pa)and tensile （TS:1.73MPa） properties. SEM indicated starch films showed a morehomogeneous phase, with the addition of Sugars. It was the addition of sugars （sucrose,fructose and glucose） to the glycerol plasticized starch-clay systems that inhibited theformation of intercalation structure by XRD and FTIR results.4、With take-up-ratio and blow-up-ratio increased, tensile properties firstly increasedthen decreased, while elongation at break showed a reverse trend. Water vapor permeabilityand transparency increased. With rising temperature, tensile properties and transparencydecreased, while water vapor permeability increased. At high temperature, Starch granuleswere disrupted and the homogeneous materials were obtained by SEM results.