超临界撞击流制备聚碳酸酯的反应动力学

Kinetics of Polycarbonate Synthesis in Supercritical Impinging Stream Reactor

研究了超临界撞击流反应器中双酚A(BPA)和碳酸二苯酯(DPC)缩聚合成聚碳酸酯(PC)的反应动力学。为了排除苯酚的内、外扩散阻力,使反应动力学仅由正向酯交换反应速率控制,对PC预聚物颗粒的粒径和CO2流量的影响进行了考察。结果表明,当预聚物颗粒粒径小于0.143 mm后,可以排除苯酚内扩散的阻力;当CO2的流量超过15 mL/min后,可以排除苯酚的外扩散阻力。在温度为90～130℃、压力为12 MPa条件下,缩聚反应在最初的6 h内为基元反应,反应级数为2级,并得到表观反应速率常数,表观活化能为46.2 kJ/mol。

The kinetics of polycondensation reaction for polycarbonate（PC） synthesized by transesterification between bisphenol-A（BPA）and diphenyl carbonate（DPC） in supercritical impinging stream reactor were investigated. In order to eliminate the internal and external diffusion resistance of small molecule by product phenol, and ensure that the kinetics is controlled by the rate of the forward transesterification reaction, the prepolymer particle size and flow rate of CO2 were chosen to ensure that the mass transfer resistance of phenol were negligible. The experimental results show that, the effect of internal phenol diffusion resistance on overall reaction rate can be negligible as prepolymer particle size is lower than 0.143 mm, and the effect of external phenol diffusion limitations can be negligible as CO2 flow rate is up to 15 mL / min. In the first 6 hours, the polymerization of PC is an elementary reaction with an order of 2, and the apparent forward reaction kinetics constants were determined at temperatures from 90 ~C to 130 ~, and pressure of 12 MPa, the apparent activation energy is 46.2 kJ/mol.