Recycling of poly lactic acid into lactic acid with high temperature and high pressure water

The converting of poly L-lactic acid into its monomer (lactic acid) was performed using high temperature and high pressure water at the temperature range of 250-350°C and for a period of 30 minutes.The results show that temperature and reaction time affected the recycling efficiency and optical selectivity.Under the tested conditions, the highest amount of lactic acid (yield of 90.7-92.5%)was obtained at temperature of 250°C and reaction time of 10-20 min.The remains were an un-harmful byproduct.A study on the effect of temperature on the optical purity of lactic acid product demonstrated L-lactic acid was predominant at a low range temperature of 250-260°C.At higher temperature, racemic mixture was observed.Based on our experimental results, the method was found to be simple and promising for recycling of poly lactic acid into its monomer, lactic acid.