Structural Design And Properties Of Polylactic Acid Composites Mediated By Ionic Liquids

Among the few mass-produced degradable thermoplastic resins,polylactic acid（PLA）is the most studied.However,PLA also has serious shortcomings,such as the processability of PLA needs to be improved,and the slow effect of crystallization rate leads to very low toughness and notch sensitivity of PLA.These shortcomings make the study of PLA modification very important.In this paper,ionic liquids（IL）with different characteristics are used as compatibilizers,and the elastomer ethylene-methyl acrylate-glycidyl methacrylate（EMA-GMA）,core-shell structure PASi-g-PMMA and degradable Polybutylene adipate-terephthalate（PBAT）is a toughening agent.The effects of IL content on the crystallization properties,mechanical properties,rheological properties and microscopic morphology of the three blends were investigated.The main results are as follows:（1）The effect of ionic liquids on the properties of PLA/EMA-GMA blends was investigated.The ionic liquid used in this part is 1-hexadecyl-3-methylimidazolium hexafluorophosphate ionic liquid.The results show that ionic liquids have plasticizing and compatibilizing effects on PLA/EMA-GMA blends.The ionic liquid can catalyze the reaction between PLA and EMA-GMA,further enhance the interfacial compatibilization reaction between PLA and EMA-GMA,and reduce the size of the EMA-GMA dispersed phase.The plasticizing effect of ionic liquid can promote the crystallization of PLA and increase the elongation at break of the blends up to 143.7%.In addition,the plasticization of the ionic liquid can reduce the melt viscosity of the blend,which provides favorable conditions for the processing and application of the PLA blend system.（2）The effects of ionic liquids on the crystallization,mechanics,rheological properties and microstructure of PLA/PASi-g-PMMA blends were studied.The ionic liquid used in this section is 1-hexadecyl-3-methylimidazole bis-trifluoromethanesulfonimide salt.DSC and DMA results showed that the 1-hexadecyl-3-methylimidazolium bis-trifluoromethanesulfonimide salt ionic liquid reduced the T_cc of the blends and played a heterogeneous nucleation role in the blend system.Ionic liquids can enhance the compatibility between PLA and core-shell particles.The impact strength of the blends increased to 858 J/m when the IL content was 1.0 wt%.SEM shows that shear yielding of the matrix is the main toughening mechanism.（3）The effects of ionic liquids on the crystallization,mechanics,rheology,micromorphology and crystallization ability of PLA/PBAT blends were studied.The ionic liquidusedinthissectionis1-hexadecyl-3-methylimidazole bis（trifluoromethane）sulfonimide salt.DSC and DMA results showed that 1-hexadecyl-3-methylimidazolium bis（trifluoromethane）sulfonimide salt ionic liquid decreased the T_g and T_m of the blends and increased the crystallinity of the PLA blends.The compatibility of PBAT is greatly improved.The addition of IL greatly improved the ductility of the blends,and SEM showed that IL could make the dispersion of PBAT smaller in the PLA matrix.