| The graft copolymers of glycidyl methacrylate (GMA) onto polylactic acid (PLA) were prepared by the melting grafting. The formation of the grafted PLA was confirmed by 1H-NMR measurement resulting in a grafting yield up to 0.73%. PLA-g-GMA was used as a compatibilizer of PLA/Starch blends and the influences of the compatibilizer on the blends were investigated using universal testing machine, DSC and SEM. The improved compatibility of PLA and starch was found due to the addition of the PLA-g-GMA, in which the starch particle dispersed in PLA matrix evenly with a size of starch particle decreased from 2-6μm to 0.5μm. Also, the mechanical properties and the water resistance of the PL A/starch blends were enhanced significantly.The graft copolymerization of itaconic acid (ITA) onto PLA was undertaken by the solution grafting method. The formation of the grafted PLA was confirmed by FTIR.resulting in a grafting yield up to 6.74%. The influences of the reaction time, initiator and ITA contents on the grafting ratio were studied. PLA-g-ITA was applied to PLA/Starch blends as a compatibilizer and the effect of the compatibilizer on the blends was studied using SEM, universal testing machine and contact angle measurement. The results show that PLA-g-ITA improved the interfacial adhesion, mechanical properties and hydrophobic of the blend effectively.Hydroxyl-terminated polylactic acid oligomers (HO-PLA-OH) were prepared by direct melt polymerization. The HO-PLA-OH was characterized by 1H-NMR, viscosity and acid value measurement. The HO-PLA-OH was blended with starch followed by a chain extending reaction using TDI as chain extender, producing in situ the high molecular weight of polylactic acid in starch matrix. The blends were characterized by FTIR, tensile strength testing, DSC, SEM and other analyses. The results show that the good compatibility of PLA/starch composite together with enhanced mechanical properties and water resistance were obtained by this approach. |
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