ABSTRACT This study aims to elucidate thermal degradation behavior and identify pyrolysis products for Nafion N115 membrane by employing nonisothermal thermogravimetric analysis, fast pyrolysis experiment with gas chromatography–mass spectrometry detection, and quantum chemical calculation. Inert thermogravimetric experiments were conducted at 5°C/min, 10°C/min, 15°C/min, and 20°C/min heating rates to obtain the mass‐loss profiles and distinguish main reaction stages. Results indicate that the overall pyrolysis process consists of drying, active pyrolysis and passive zones, of which the active pyrolysis zone has the maximum weight loss of 72.8% within 295°C–509°C. Accordingly, six model‐free methods were employed to calculate the activation energies as a function of conversion. Both linear and nonlinear model‐fitting methods were applied to determine the most appropriate reaction model for the main degradation stage within 0.19 < α < 0.77. By fully considering the kinetic compensation effect, the linear relationship between activation energy E a and neutral logarithm of pre‐exponential factor ln A was obtained by employing 19 classical models. Therewith, the optimal mechanistic model, f ( α ) = 379.7286 α 0.00127 (1 − α ) 1.9494 , was reconstructed based on D3 diffusion‐controlled model by using Sestak–Berggren method. Theoretical calculations uncover thermal stability and reactivity for all chemical bonds supported by HOMO–LUMO energy gaps. Ultimately, structural identifications of 13 pyrolysis products were qualitatively performed by using gas chromatography–mass spectrometry. All results offer insight into the proper processing and application for Nafion series membranes.
Yang et al. (Tue,) studied this question.