The Effect Of Functional Ionic Liquids (ILs) On The Thermal Behavior Of Polylactide (PLLA)

In this paper, seven different kinds ionic liquids,[HOEMIm]BF4,[AOEMIm]BF4,[EOEMIm]BF4,[BMIm]BF4,[EOEMIm]NO3,[EOEMIm]Br and[EOEMIm]PF6, were synthesized, they could be classified according to thetypes of cations and anions. Each ILs were solution blended with poly(L-lactide)(PLLA) in several different content to evaluate the effects of them on the thermaldegradation of PLLA, which were investigated by means of thermogravimetricanalysis (TGA). In kinetic study, the thermal degradation activation energy (Ea) ofPLLA/ILs were calculated by Kissinger, Ozawa and Friedman methods. Málekmethod was used to measure the kinetic functions of PLLA andPLLA/3[EOEMIm]BF4. ILs could reduce the thermal degradation temperature ofPLLA, and the cations play much more important roles, which could change thecourse of PLLA thermal degradation. In the probable kinetic functions studies, theaddition of IL i.e.[EOEMIm][BF4] to the PLLA has a pronounced effects on itspyrolytic degradation, facilitating the transesterification as evident from the resultsobtained by applying Avarami-Erofe’ev (A3) model.Another kind of imidazolium-based ionic liquid with topology structuregrafted with MPEG segment (TSIL) was also blended with PLLA. In the studyof PLLA/TSIL blends melt behavior, TSIL could form a certain degree ofcross-linked network structure with PLLA by transesterification. TSIL could alsodecrease the PLLA thermal stability.Tris-(3-methylimidazolium chloride-2-carboxyethyl)phosphine ([TCEPMIm]Cl)was used to modify multi-walled carbon nanotubes (MWCNTs). Then the modifiedMWCNTs was blended with PLLA, the melt crystallization and thermal stability ofthe ternary nanocomposites were studied, the flammability were evaluated bycone calorimeter test.[TCEPMIm]Cl-MWCNTs could improve the crystallinity ofPLLA and improve the rapidest degradation temperature, but decrease the onsetdegradation temperature. The composite showed a45%reduction in peak heatrelease (HHR) when tested in the cone calorimeter. It revealed that the obvioussynergistic effect between [TCEPMIm]Cl and MWCNTs was very efficient inimproving the flame retardance of PLLA composite.