Study On Hydrolysis Of Polylactic Acid And Polycaprolactone

Different kinds of ionic liquids were synthesized and characterized by FT-IR and NMR. The dissolubility of polylactic acid (PLA) and polycaprolactone (PCL) in different ionic liquids were investigated, the results showed that there was a good solubility of PLA in [Bmim][Ac] and there was a good dissolubility of PCL in [Bmim][Ac] and [HSO3-pmim][HSO4].The hydrolysis of PLA was investigated using ionic liquids as catalyst and solvent. The effects of reaction temperature, reaction time, water dosage and [Bmim][Ac] dosage on the hydrolysis reaction were examined. It was shown that the hydrolysis rate of PLA was nearly94%, and the yield of calcium lactate was over76%under the following conditions:reaction temperature130℃, reaction time2.0h, n(H2O):n(PLA)=6:1and m([Bmim][Ac]):m(PLA)=0.5:1. The structure of obtained product was characterized by FT-IR. The ionic liquid could be reused up to7times with no apparent decrease in the hydrolysis rate of PLA and yield of calcium lactate. The kinetics of the reaction was also investigated. The results indicated that the hydrolysis of PLA in [Bmim][Ac] was a first-order kinetic reaction with an activation energy of133.9kJ/mol. The reaction mechanism of PLA hydrolysis in ionic liquid [Bmim][Ac] was proposed.The hydrolysis of PCL was investigated using ionic liquids as catalyst and solvent. The effects of reaction temperature, reaction time, water dosage and [Bmim][Ac] dosage on the hydrolysis reaction were examined. It was shown that the conversion of PCL was nearly84%, and the yield of6-hydroxycaproic acid was over72%under the following conditions:reaction temperature170℃, reaction time3.0h, m([Bmim][Ac]):m(PCL)=0.625:1and n(H2O):n(PCL)=5:1. The structure of obtained product was characterized by FT-IR. The ionic liquid could be reused up to6times with no apparent decrease in the hydrolysis rate ofPCLand yield of6-hydroxycaproic acid. The kinetics of the reaction was also investigated. The results indicated that the hydrolysis of PCL in [Bmim][Ac] was a first-order kinetic reaction with an activation energy of140.9kJ/mol. The reaction mechanism of PCL hydrolysis in ionic liquid [Bmim][Ac] was proposed.