Extrusion Blowing And Properties Of Starch-based Composite Films

The composite films by extrusion blowing were prepared from hydroxypropyl distarchphosphate （HPDSP） and cationic starch （CS）, adding poly（vinyl alcohol）（PVA）, respectively.The main results were as follows:1. Effects of PVA content on properties of starch films. Both HPDSP and CS were wellcompatible with PVA. The crystalline structure of either starch or PVA had collapsed afterthey were blended to extrude. With the addition of PVA, HPDSP/PVA films showed bettermechanical properties, better barrier properties to water vapor as well as better lighttransmittance. HPDSP/PVA films containing15%PVA had better properties.2. New hydrogen bonds were formed as nanomaterials interacted with starch/PVA system.The properties of starch films were improved with the addition of nanomaterials. The filmwith OMMT showed the greatest tensile strength （7.04MPa）, best barrier properties to watervapor (4.12×10^-10g·m^-1·s^-1·Pa^-1), and highest thermal stability （lowest weight loss）. The filmwith nano-CaCO3showed the best heat sealability. Both nano-SiO2and OMMT were welldispersed throughout starch/PVA matrix. And they were more suitable for the preparation ofstarch/PVA nanocomposite films as an intensifier among all the five nanomaterials.3. Epoxidized soybean oil （ESO）, epoxy fatty acids methyl ester （EFAME）, and acetyltributyl citrate （ATBC）, respectively, was blended with glycerol （GLY） as mixed plasticizers.Mixed plasticizers could alter the glass transition temperatures （Tg） of the films. Thecrystallinity of starch/PVA films decreased with the addition of environmental plasticizers.Film plasticized with ATBC/GLY, enhanced with OMMT, exhibited the highest tensilestrength and lowest WVP. Moreover, compared with other films, no residual granularstructure of starch was present in this film. These results indicted that ATBC/GLY was themost effective for starch/PVA/OMMT films.4. Effects of various proportions of ATBC/GLY on properties of starch/PVA/OMMTfilms. With the increase in the proportion of ATBC, the films showed the lowest WVP(3.01×10^-10g·m^-1·s^-1·Pa^-1) and the highest tensile strength （6.81MPa）, however, theelongation at break decreased. The plasticizing effect of the mixed plasticizers decreased asthe increase in the proportion of ATBC. Starch/PVA/OMMT films formed different degree ofintercalated nanocomposite structure.