Modeling and Simulation of Reaction–Mass Transfer Coupling Kinetics for Industrial-Scale Poly (Butylene Succinate-Butylene Terephthalate) Polycondensation Process

Poly (butylene succinate-butylene terephthalate) (PBST) is a novel high-performance degradable copolyester that combines the advantages of aliphatic polyester and aromatic polyester. This study investigated the intricate reaction kinetics and mass transfer in the PBST polycondensation process using static thin-film experiments. The findings suggest that the apparent reaction rate escalates with increasing temperature, decreasing pressure, and thinner film thickness. Based on the pseudo-steady state assumption, an overall apparent rate model encompassing both reaction kinetics and mass transfer was formulated, and the model was employed to simulate the coupling effects of reaction and mass transfer on the PBST polycondensation process. The simulation results reveal that film thickness has the most significant effect on the degree of side reaction. Film thickness primarily influences the accumulation of BDO(1,4-Butanediol) in the melt during the early stages of the reaction, where BDO accumulates in the melt and intensifies the side reaction under thicker film. And pressure has the most substantial influence on the concentration of BDO as the reaction approaches equilibrium. Additionally, the sensitivity of the growth of molecular weight to pressure is notably higher at low film thickness.