Structure and performance of poly (lactic acid)/amide ethylenediamine tetraacetic acid disodium salt intercalation layered double hydroxides nanocomposites

Modified layered double hydroxides (E-LDHs) were successfully prepared by the intercalation of ethylenediamine tetraacetic acid disodium salt (EDTA). Then, amide EDTA intercalation layered double hydroxides (AE-LDHs) were synthesized using aniline. The structure characterization of AE-LDHs demonstrated that AE-LDHs was successfully amidified. To enhance the properties of poly (lactic acid) (PLA), PLA/AE-LDHs nanocomposites were prepared by using AE-LDHs as the nucleating agent. Mechanical properties, thermal stabilities and crystallization properties of PLA/AE-LDHs nanocomposites were investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheological behavior analysis. Results of mechanical properties and TG analysis showed that mechanical properties, thermal stabilities of PLA/AE-LDHs nanocomposites were improved significantly compared to pure PLA. Differential scanning calorimetry (DSC) demonstrated that AE-LDHs restricted the cold crystallization of PLA matrix and improved the crystallinity of PLA by 30.15%. POM analysis showed that AE-LDHs acted as an excellent nucleating agent, which greatly increased the crystallization rate of PLA. Compared with pure PLA, the maximum torque and apparent viscosity of PLA/AE-LDHs nanocomposites were improved by 46.21% and 85.86%, respectively, which proved that the AE-LDHs increased the rigidity of network structure of PLA matrix. In this work, an efficient and feasible nucleating agent for improving the crystallinity of PLA was presented through the amidation of LDHs.