The Research Of Modeling In Batch Reaction Process Of Polycarbonate

Polycarbonate is a kind of typical thermoplastic polymer. Due to its outstanding comprehensive performance, it is widely used and is very promising in future market. At present, there are mainly two methods in the synthesis of PC:interfacial polymerization and melt transesterification. The former is widely used in the most industries (about90%) in the world with the advantages of the low reaction temperature and the low energy consumption, which can also get PC of various grades. PC is mainly producted by interfacial polycondensation phosgene method, namely BPA and phosgene react in the interface of organic phase and aqueous phase.At present, batch production mode is used mostly in the production of polycarbonate,The product molecular weight fluctuation of different batches is larger because of the influence of the operation process and human factors, which affect the final product quality. If the molecular weight of each batch reaction process is monitored, people can found molecular weight of the moment deviates from normal, and adjust the feed flow rate in time to achieve normal finally product molecular weight.It has great significance to improve the quality of our products. Now advanced process control (also known as the advanced control) is a relatively mature control technology. It can realize the monitoring and control of molecular weight, but this kind of control method must be based on the mathematical model. Therefore, the establishment of polycarbonate reaction dynamic model of the process is of great significance.First, the reaction mechanism of polycarbonate in organic phase is investigated in detail. The apparent rate of polycarbonate polymerization process is decided by the reaction rate and mass transfer rate jointly. Mass transfer rate and reaction rate of BPA sodium salt and phenol and phosphates both in water phase and organic phaseare are researched.Reaction kinetics rate equation was established according to reaction mechanism. Combined with moment rate equation and convective mass transfer mode, Reaction process model of Synthesis of polycarbonate by the interfacial polycondensation is established.Secondly, the parameters in the model are identified according to the pilot test data. Using the four order Runge-Kutta method, simulation calculation is carried out. Simulation results were compared with the test data. The polycarbonate number average molecular weight was consistent with the test results. This proves that the model has good accuracy, and it can describe the real reaction process.Finally, using polycarbonate reaction process model analyses the reaction process. Changes in datas of matter content in the organic phase and water phase, the number-average molecular weight and weight-average molecular weight are studied when feeding speed of the BPA sodium salt, phosgene and phenol content is different. According to the results of the analysis, mathematical model can Adjust and control Molecular weight of the reaction process, and provide a model or datas for the application of advanced control in the synthesis of PC.