vacuumized and charged with nitrogen for three consecutive times for air removal and then was allowed for bulk polymerization which comprised a first reaction stage and a second reaction stage in the first reaction stage a reaction temperature was 125 u00b0 c a reaction pressure was 0 4 torr a reaction time was 16 hours and a resulting product was medium molecular weight poly l lactic acid m plla having a weight average molecular weight mw of 5 0 u00d7 10 4 thereafter the second reaction stage was followed where a reaction temperature was 140 u00b0 c a reaction pressure was 0 1 torr a reaction time was 40 hours and a final product was a high molecular weight poly l lactic acid h plla having a weight average molecular weight of 5 0 u00d7 10 5 the final product has the following performance index mw 5 0 u00d7 10 5 pdi 1 54 tm 187 4 u00b0 c xc 82 1 and snowy white in color 150 0 g of lla 4 5 mg of arginine and 4 5 mg of k 2 co 3 were added to a polymerization reactor the polymerization reactor was vacuumized and charged with nitrogen for three consecutive times for air removal and then was allowed for bulk polymerization which comprised a first reaction stage and a second reaction stage in the first reaction stage a reaction temperature was 125 u00b0 c a reaction pressure was 0 4 torr a reaction time was 16 hours and a resulting product was medium molecular weight poly l lactic acid m plla having a weight average molecular weight mw of 5 0 u00d7 10 4 thereafter the second reaction stage was followed where a.