乳酸直接缩聚制备聚乳酸的动力学

Kinetics of direct polycondensation preparing polylactic acid by using lactic acid

研究了乳酸直接缩聚制备聚乳酸的反应动力学,结果表明:在常压和无催化剂条件下,当温度达到124℃时,乳酸单体开始缩聚,在反应程度为14.15%～62.75%的范围内缩聚反应符合3级反应,其动力学方程式为-d[COOH]/dt=1.057×10-5[COOH]3。还计算了在不同温度下的反应速率常数k,并根据ARRHENNIS公式求得反应活化能E=4.34 kJ.mol-1。最后,比较了理论计算与实际测量的数均分子量与时间的关系。

Reactive kinetics of direct polycondensation of lactic acid was studied, The direct polylactic acid（PLA） was made from lactic acid under atmospheric pressure and with no catalyst. The results show that the polycondensation of lactic acid proceeds as a third order reaction at 124 ℃ with 14.15%-62.75% conversion and according to a kinetic equation： -d[COOH]/dt=k[COOH]^3. The rate constant of reaction, k, at different temperature and the activation energy E of 4.34 kJ/mol were calculated. Finally the relationship of number-average molecular mass to time have been compared by using theoretical calculated and practical measured values.