Abstract: The kinetics of polycondensation of lactic acid has been investigated. The resuIts showed that in the absence of catalyst the polycondensation proceeds as a third order reaction at 124℃ with 10%～60%conversion:-d[COOH]/dt=1.32×1O-5[COOH]3. In the pres-ence of ca.1%(wt) of a strong acid ion-exchange resin at 120℃and 10%～50%of conver-sion the polycondensation follows a second order equation:-[COOH]/dt=1. 51 ×10-4[COOH]2.Addition of the catalyst decreased the activation energy of the reaction and thepolycondensation could be initiated at a lower temperature. The reaction showed a maximumrate as the amount of the catalvst was about 1%(wt)of the lactic acid.

Key words: lactic acid, polycondensation, kinetics