Improvement in Purification Method of a Synthesized Cyclic Dimeric Lactide
Lactide was synthesized by reverse polymerization of low molecular weight poly(lactic acid) with two different molecular weights:1500 and 2500. Two different lactide purification processes such as: recrystallization in ethyl acetate and washing the crude lactide with ether before recrystallization in ethyl acetate were evaluated. It has been demonstrated that increasing the molecular weight of poly(lactic acid) does not influence the production yield, melting point and optical rotation of lactide. The washing of crude lactide with ether and recrystallization in ethyl acetate can be carried out in a short period of time (within 1 day) at a high yield (35%) using less solvent. In contrast, the first purification method gives lower (11%) production yield by using higher amount of solvent at longer time. It is also found that the purification methods do not have any specific effect on the properties of lactide.
کلیدواژه ها [English]
lactide, poly(lactic acid), purification, crystallization, melting point