Chemical degradation of elastomeric gasket material in simulated PEM fuel cell environments

摘要

The gaskets in PEM fuel cell are typically elastomeric material and are exposed to acidic liquid solution, humid air and hydrogen. Therefore, the stability and durability of the gaskets are critical to both sealing and the electrochemical performance of the PEM fuel cells during long-term operation of the PEM fuel cells. In this paper, the chemical degradation of a commercially available gasket material, silicone rubber, was investigated in the simulated PEM fuel cell environments. Weight loss was monitored for the sample exposed to the simulated PEM fuel cell environments. Optical microscopy was used to examine the surface conditions of the samples after exposure to the environments over time. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the gasket material before and after exposure to the simulated PEM fuel cell environments. The results show that the weight loss increased with the exposure time for the samples. The optical microscopy reveals that the surface conditions of the samples changed gradually with exposure time from initially smooth to rough, crack appearance and finally crack propagation. The ATR-FTIR test results indicate that the surface chemistry changed significantly and the chemical degradation mechanism could be de-crosslinking and chain scission in the backbone for the samples after exposure to the simulated PEM fuel cell environments. It is found that the environment had a significant effect on the degradation of the samples.