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摘要

A process for synthesizing medical biodegradable polylactic acid by creatinine catalysed lactic acid condensation, comprising (A) using 85-90% aqueous lactic acid solution as a monomer, feeding the lactic acid into a reaction kettle, then repeating the operation of evacuation-argon filling three times, heating the reaction kettle to 130-150°C under an argon atmosphere and a normal pressure to perform dehydration for 1-6 hrs, reducing the pressure in the reaction kettle to 100 Torr and continuing the reaction for 1-6 hrs at 130-150°C, then reducing the pressure in the reaction kettle to 30 Torr and continuing the reaction for 1-6 hrs at 130-150°C to synthesize the oligomeric lactic acid, and (B) using the oligomeric lactic acid as the raw material and a commercial creatinine as a catalyst, controlling the molar ratio of creatinine to lactic acid at 1 : 590, feeding the catalyst creatinine into the reaction kettle, then reducing the pressure in the reaction kettle to 10 Torr and increasing the reaction kettle temperature to 150-190°C to perform a reaction for 48-96 hrs.