Review on physical and chemical properties of low and high-temperature polymer electrolyte membrane fuel cell (PEFC) sealants

Sealants (or gaskets) play an exceptional role in the efficient functioning of polymer electrolyte membrane fuel cells (PEFCs). They prevent leakage of reactant gases and coolants from the perimeter of cell. Also, they circumvent the direct mixing of reactant gases in the active region of the PEFC. Sealants ensure electrical insulation, preventing a short circuit between anode and cathode of the PEFCs. Sealants enhance the safety, thereby improving the functional performance of the PEFCs. In addition, the sealants have functional requirements that contain excellent physical and chemical properties to withstand the working conditions of PEFCs. Hence, the physical and chemical properties of the sealants are crucial for improving the sealing capability as well as the performance of PEFC. In this article, properties such as weight loss, indentation load, elastic modulus, hardness, hysteresis loss, chemical composition and chemical structure of well-known PEFC sealants are reviewed. These PEFC sealants are classified into low-temperature PEFC (LT-PEFC) and high-temperature PEFC (HT-PEFC) sealants, depending on the operational temperature. The polymeric materials such as silicone rubber, fluoroelastomers (FKM), ethylene propylene diene monomer (EPDM) rubber, polytetrafluoroethylene (PTFE) rubber, etc. are found to be suitable sealant materials for PEFCs.