PET固相缩聚工艺与反应动力学机理研究

Studies on Solid-state Polymerization of PET and Reaction Kinetics Mechanism

在真空或氮气条件下,研究了聚对苯二甲酸乙二醇酯(PET)的固相增黏反应,通过分析增黏后的PET特性黏度和端羧基含量的变化探讨其反应动力学。结果表明:随着反应温度升高或反应时间的延长,PET特性黏度均不断增大,而端羧基含量则不断降低。当反应刚开始时,反应温度低,特性黏度变化缓慢;随反应温度逐渐升高,水和乙二醇等副产物在氮气或抽真空作用下快速带出反应体系,使得特性黏度增长趋势加快。然而当温度高于230℃时,PET样品容易发生粘结,从而限制了小分子的排出,特性黏度增长速度趋于缓慢。反应动力学研究结果表明固相缩聚符合二阶反应动力学模型,根据Arrhenius方程计算了固相缩聚反应速率和反应的活化能。

The solid-state polymerization reaction （SSP） of polyethylene terephthalate （PET） was studied under vacuum or nitrogen conditions. Its reaction kinetics was discussed through analyzing the changes of intrinsic viscosity and the carboxyl group content of PET. The experiment results show that the intrinsic viscosity of PET increased with the increment of the reaction temperature and time. However, the carboxyl content reduced continuously. When the reaction started, intrinsic viscosity changed slowly due to low reaction temperature. As the reaction temperature increased gradually, by-products such as water and glycol were removed from the reaction system fast by nitrogen or vacuum, so the intrinsic viscosity increased rapidly. When the temperature was higher than 230 ℃ ,intrinsic viscosity growth trend got slower, because PET samples were easily bound to limit discharge of micromolecules. Reaction kinetics research results show that solid-state polymerization reaction conformed to second order kinetic model. At the same time,the solid-state polymerization reaction rate and the activation energy were calculated in the study according to Arrhenius equation.