Simulation of irreversible and reversible degradation kinetics of linear polymers using sectional moment method

Abstract

In the field of polymer reaction engineering, accurately simulating polymer degradation process is beneficial to understand the reaction kinetics, which guides the design, operation, and control of the degradation reactor. Herein, a sectional strategy based on the method of moments with a newly defined critical chain length was proposed to simulate the degradation process of linear polymers with low computational cost. By accounting for the concentration of species with low molar mass (e.g., dimer), the evolution of average properties and concentration polymer species during linear polymer degradation were simulated with high accuracy through this model. In addition, the evolution of molar mass distribution was approximated by using the as-developed model. Sensitivity analysis was performed for simultaneous random scission and irreversible/reversible chain-end scission processes. Results show that monomer yields, average and distributed molecular properties can be tuned by the rate coefficients of random scission (kr), chain-end scission (ke), and its reverse reaction (k-e). Finally, kinetic insights into the polylactic acid alcoholysis system were gained by the as-developed MoM-based model, which demonstrates the accuracy and applicability of the model. This work provides a new method for simulating linear polymer degradation, and thus revealing the kinetic evolution during degradation.