PBI membranes via the PPA process

Abstract

The Polyphosphoric Acid (PPA) process has greatly impacted many aspects of phosphoric acid imbibed polybenzimidazole (PBI) films. The ability to cast the PBI solution directly from PPA not only improves manufacturability, but allows for various chemistries of PBI to be synthesized by overcoming some of the solubility limits seen in the traditional synthesis and imbibing process. PBIs prepared via the sol-gel PPA process exhibit high inherent viscosities (I.V.), good mechanical properties, and higher acid loadings and ionic conductivities than those produced by other methods. Extensive fuel cell testing has shown that PBI membranes are applicable to many fuel cell devices, and possess the durability in different simulated operating environments to remain at the forefront of high-temperature polymer membrane fuel cell applications.