An Improved PO3G Model–Accounting for Cyclic Oligomers

A comprehensive model is developed for polycondensation of 1,3‐propanediol in a batch reactor. The model accounts for formation, consumption, and evaporation of cyclic oligomers. Measurements of species and end‐group concentrations in the reactor and collected condensate are used to estimate 36 kinetic and mass‐transfer parameters. The model and parameter estimates provide good fits to cyclic‐oligomer data obtained using four different levels of super‐acid catalyst. Predictions from the model reveal that end‐biting reactions are important for formation of cyclic oligomers during early stages of each batch‐reactor run, whereas back‐biting reactions become important at longer reaction times. Simulation results reveal that ring‐opening polyaddition reactions contribute significantly to growth of polymer chains at long reaction times. A comprehensive model that accounts for cyclic oligomers is developed for polycondensation of 1,3‐propanediol. Model equations and parameter estimates result in good fits to industrial data. Simulation results reveal that end‐biting and back‐biting reactions are both important for formation of cyclic oligomers, and that ring‐opening polyaddition reactions contribute significantly to growth of polymer chains.