ABSTRACT
Vogel and Marvel [1] synthesized the first aromatic polybenzimidazoles (PBIs) in 1961. Because this polymer showed exceptional thermal and oxidative stability, National Aeronautics and Space Administration (NASA) and Air Force Material Laboratory sponsored DuPont and Hoechst Celanese to undertake fundamental research works on this material in the early stages of the development for aerospace and defense applications. Before the 1980s, major applications of PBI were in fire-blocking applications, thermal protective clothing, and reverse osmosis (RO) membranes. Its applications became diverse by the 1990s; molded PBI parts and microporous membranes were developed. The former exhibited superior performance as sealing elements in high-temperature corrosive environments. Hoechst Celanese commercialized PBI in 1983. Today, PBI Performance Products Inc. (https:// www.pbiproducts.com/) is the major producer of high-performance PBI materials.
