The Research On Synthesis And Degradation Of Poly(D,L)lactic Acid And Poly(D,L)lactic Acid-Polycaprolactone

Lactide and polycaprolactone (PCL) were used to prepare and change property of poly(D,L) lactic acid. The degradations of PDLLA and PLA-PCL were studied in this paper.The key of indirect method to synthesize PDLLA was the preparation and purification of intermediate lactide (DLLA). The synthesis technics of DLLA and PDLLA was investigated by orthogonal experimentation. The affections on the yield of DLLA and molecular weight of PDLLA caused by catalyst, time and temperature etc. were studied and the optimal conditions were made sure the shorter reaction time, 31.1% yield and 110000 mocular weight with catalyst content 2.2%, dehydrate time 3h, dehydrate temperature 130℃, polymer-opening temperature 240℃in synthesize of DLLA and polymeric temperature 170℃, polymeric time 4h, catalyst concentartion 0.06 in synthesize of PDLLA. The DSC, 1H-NMR and IR were used to characterize and analyze DLLA and PDLLA. The hydrolytic degradation of PDLLA was investigated. The higher of molecular weight, the slower of degradation.Caprolactone was used to change property of PDLLA by copolymerization and coblend. In copolymerization, the affections on the molecular weight of copolymerization caused by catalyst, temperature and time etc. were studied, the right conditions, reaction temperature 130℃, reaction time 48h,catalyst content 0.8%, were confirmed for copolymerization. the DSC, 1H-NMR and IR were used to characterize and analyze copolymerization. In coblend, the direct coblend and coblend with PLA-co-PCL were compared by SEM, the coblend with PLA-PCL was better than direct coblend. In comparison with PDLLA, the degradation of copolymerization and coblend in NaOH solution was investigated and the degradation of copolymerization and coblend was slower than PDLLA. The higher of the PCL content, the slower of degradation.