About 8 years ago, Brinker and Robinson [l] invented the first aliphatic polybenzimidazoles. Two years later, aromatic polybenzimidazoles with impressive thermal properties were synthesized by Vogel and Marvel [2, 3] at the University of Illinois and later at Du Pont. Since then, high performance polybenzimidazoles received a great deal of attention by academia, U. S. government, and industry. Various new polybenzimidazoles have been invented, as reviewed in Refs. 4–12. Hoechst Celanese commercialized polybenzimidazole fiber for thermal protective clothing and fireblocking applications in 1983. In the mid 1980s, both Hoechst Celanese and Alpha Performance Company developed the technology to mold polyben- zimidazole parts (under the trade name of Celazole®). Alpha took over Celazole® technology completely in 1995 and continued marketing polybenzimidazole molded parts as sealing elements in high-temperature corrosive environments. Poly (2,2′-(m-phenylene)-5,5′ bibenzimidazole) is their product composition and is referred to as PBI.