Improvement on Direct Polycondensation of Polylactic Acid

The direct polycondensation methods along with the improved process of catalysts, dehydration, nitrogen and vacuum were adopted to synthesize the biodegradable material of polylactic acid (PLA) from D, L-lactic acid. The influence of different catalysts and the amount of catalysts, temperature and time of polymerization, vacuum and polymerization process on the molecular weights of PLA was discussed. The optimum reaction condition was that the contet of stannite caprylate was 0.5 phr,polymerized at 175℃ for 12h,in vacuum of 30 pa.The synthesized PLA had no oxidation and color deterioration, and the viscosity average molecular weight of which was up to 20800 g/mol.