超临界甲醇中聚对苯二甲酸丁二酯分解动力学研究

Kinetic Analyses of the Decomposition of Poly (butylene terephthalate) in Supercritical Methanol

在超临界甲醇中对聚对苯二甲酸丁二酯(PBT)进行了分解反应动力学的研究。在300℃,12MPa,甲醇与PBT的投料比为5.8的实验条件下,采用端基分析的方法测定出分解产物中羧甲基的含量,并建立了羧甲基的含量与反应时间的对应关系; 根据求解的反应速率常数k(0.4319)、反应平衡常数K(0.5780),建立了超临界甲醇中PBT分解的动力学方程。在不同的反应时刻,方程计算值与实验值比较的结果显示,二者具有相同的变化趋势,其偏差在5.08%以内,认为该方程可用于描述在超临界甲醇中PBT的分解过程。在此基础上求解分解反应的活化能,在260～330℃的温度范围内得到分解反应的活化能为34.51kJ mol-1,低于相关文献所报道的值。

The alcoholysis kinetics of poly(butylene terephthalate) (PBT)in supercritical methanol was studied. On the conditions of 300°C, 12 MPa and the ratio of methanol /PBT of 5.8, the content of carboxymethyl group was determined by analyzing end group. The content dependence of carboxymethyl group on reaction time was obtained. The kinetic equation about the alcoholysis of PBT was set up referring to the chemical equilibrium constant K (=0.5780) and chemical recitation rate constant k (=0.4319). At different reaction time, the experimental value had the same tendency with the calculated value, and the error between them was less than 5.08%, so the equation could be used to describe the decomposition process. The value of apparent activation energy was calculated with Arrhenius equation in the span of 260°C - 300°C, which gave a value of 34.51 kJ&middotmol-1. The value was lower than that in the related report.