Preparation And Properties Research On Blends Of PLA/Acetate Starch

In this paper, nano-SiO2gel (GS) was prepared with nano-SiO2dispersed in glycerol (GL), which was melting blent with polylactic acid (PLA)/starch acetate (SA) to prepare PLA/GS-SA blend in order to further improve its mechanical properties and resistance to water. Then, the effect of GS had been studied on the mechanical properties, the thermostability, the resistance to water and the micro-morphology of the melt blends of PLA/GS-SA in different concentrations and contents. The results showed that mechanical property of the blend was improved obviously due to the hydrogen bonding between the hydroxyl both in the surface of nano-SiO2and in SA molecules, such as when the concentration of GS was15wt%, the tensile property reached the maximum and was24.17MPa. At the meanwhile, it’s found that nano-SiO2could reduce the saturated water absorption and increase the time of it by50%, indicated that nano-SiO2could actually improve the resistance to water and the thermostability of the starch-based material.To further improve compatibility and tensile property of the PLA/SA blend, the ternary alloying blend of polyvinyl (PVA)/PLA/SA was prepared in an internal mixer by the melt blending PVA. The influence of PVA had been investigated on mechanical properties, thermodynamic properties, resistance to water and micro-morphology of the ternary blends with or without GL in various particle sizes, molecular weights and contents. It was indicated that there was continuous marcophase between PVA and SA, which was much more stable while there was larger particle size, higher molecular weight or higher content of PVA. It improved the mechanical properties of the ternary alloying blend, thus the tensile reached the maximum and was25.85MPa. However, the resistance to water declined with more PVA content and was not related to molecular weight of PVA.In order to improve flexibility of blend, G-POE was added into the ternary alloying blend of PVA/PLA/SA, and the effect of the additional of G-POE was discussed. AS the result showed, the mechanical properties of the blend, especially the impact strength, were enhanced significantly by the addition of G-POE, e.g. the maximum tensile strength was up to33.09MPa and the maximum impact strength was9.04kJ/m2. It’s verified that there was strong interaction such as the reaction or the hydrogen bonding between G-POE and the substrate by SEM and DMA, which made the interface between phases tightly to improve the performance of the blend. At the same time, it’s found that G-POE could reduce both the beginning and the saturated water absorptions of the blend, increase the surface contact-angles and remain it around80°, indicated that the resistance to water of the starch-based material could be improved by the addition of G-POE.