Change of mechanical properties of e-PTFE support by electrochemical degradation in polymer electrolyte membrane fuel cell

Abstract In polymer electrolyte membrane fuel cell (PEMFC), the cost and durability are main challenges to commercialization. To achieve the long-term durability target, the durability of PEMFC materials should be further improved. In this paper, we investigated the chemical and electrochemical degradation of the expanded polytetrafluoroethylene (e-PTFE) support and examined how it influences the mechanical properties of the e-PTFE support. We conducted the Fenton test and open circuit voltage (OCV) holding and analyzed the chemical and physical structural changes of the e-PTFE support by utilizing Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and tensile test. After the chemical and electrochemical degradations, the molecular bonds of e-PTFE were broken, and the microstructures of e-PTFE were deformed. As the result the mechanical properties of e-PTFE showed significant decrease. Consequently, our results show that the e-PTFE support is deteriorated chemically during PEMFC operation, and this chemical degradation lead reduction of mechanical strength.