The thermal behavior and pyrolysis mechanism of a polyimide gas separation membrane

Polyimide (PI) membranes have shown great advantages in gas separation due to their excellent thermal and chemical stability as well as high separation performance. With the increased demand for PI membranes, their recycling is a challenge for sustainable development. In this work, we systematically studied the pyrolysis behavior and performed kinetic analysis of a Kapton polyimide membrane, which has been suggested to exhibit a high gas separation performance. Results showed that the pyrolysis of the polyimide membrane was divided into three stages revealed by Py-GC/MS, with the main products being CO2, CO, and H2O. To study the pyrolysis kinetics of the polyimide in the main conversion range, the FWO, KAS, and Starink methods were adopted. The average activation energies were found to be 284.6, 286.1, and 286.5 kJ mol−1, respectively. The pyrolysis of the polyimide membrane followed second-order (F2) and third-order (F3) models. Consequently, the pyrolysis technique provides valuable guidance for the recycling of polyimide membranes.