Aging of the gasket materials in simulated PEM environment and accelerated mediums

Silicon rubber is a potential material for gaskets in proton exchange membrane (PEM) fuel cell. So its long term stability and durability is crucial to the electrochemical performance of fuel cell especially in acidic, high temperature and humid environment. In present paper, the aging process of silicon rubbers has been studied in one simulated PEM fuel cell medium and two accelerated durability test (ADT) mediums for short time test at 70°C and 90°C, respectively. Effect of exposure time, temperature and exposure medium on aging of silicone rubber is also compared. Weight loss is measured by electronic balance, and topographical changes on samples' surfaces are monitored by optical microscopy. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of samples before and after exposure over time. The results show that the weight loss increases over time. Surface conditions of samples change over time from initially smooth to rough, crack appearance and finally crack propagation through Optical microscopy. ATR-FTIR results show that the surface chemistry change significantly via de-crosslinking and chain scission in the backbone for materials over time. The aging degree is severe at high temperature or in high concentration acidic solution over time.