Polylactic Acid Synthesis Study

This thesis primarily studied the technologcial conditions of synthesization of lactide and ring-opening polymerization of PLA.We use the method of decomposing PLA to synthesize lactide by means of orthodoxical experiment method. By exact experiments we got the relationship between dehydration time, dehydrationing temperature, decomposing temperature and the rate of synthesizing lactide. The best techinical method of increasing the rate of product.Under conventional pressure, using the lactide synthesized by ourselves, catalyzeing by Sn(Oct)2 we investigate the relation of both the temperature of reaction, the time of reaction, catalyst and the molecular weight of the synthetic PLA.We investigate how the type of lactide affacts the molecular weight of PLA at the same time.Finally passing to adjust the reactive conditions ,we get the molecular weight amounting to 110,000 of PLA with the rate attaining about 90% of producing PLA under conventional pressure, and characterize the PLA.This paper also discusses the direct polymerization of PLA by lactic acid simplely.Finally, the thesis gave expectancy to the method of increasing the molecular weight of PLA obtained under conventional pressure. It was hopefully to get much higher Mw PLA.