Direct Polycondensation Of The Legal Preparation Of Biodegradable Material Polylactic Acid Research

The methods of producing biodegradable materials ?PLA by the direct condensation polymerization was studied. As having carboxyl and hydroxide, Lactic acid accords with the main qualification of the direct condensation polymerization. And the IR spectra of PLA produced by the condensation polymerization is same to that polymerized by the ring-opening polymerization. So the direct condensation polymerization is theoretically feasible, and the studies to develop a feasible process for the commercial production of PLA and its application to some other aliphatic polyesters is realistically significative.PLA has been. conventionally produced by a multi-step process, including the isolation of an intermediate dilactide (a cyclic dimer of lactic acid) followed by a ring-opening polymerization. But this method is expensive and complicated for it includes many time-consuming and funds-consuming processes.In order to approach to the desired process for a high-molecular-weight polylactic acid, we concentrated on testing a variety of catalysts, dosage of catalysts, solvents, the weight ratio of solvents to LA, reaction temperatures, reaction pressure, reaction time, and different equipment of experiments and so on. The characteristic features of polylactic acid obtained by this direct process were compared to that obtained by the conventional ring-opening polymerization process.The novel direct polymerization method was established for the first time accessing to the higher-molecule-weight PLA. Due to its easy approach to the commercial production and the excellent biodegradable feature of the PLA, our direct polymerization method may open the door for the new market.