Polybenzimidazole fiber

Polybenzimidazole or PBI is an aromatic polyimide with a very high melting point.

History

Polybenzimidazole was originally synthesized in the late 1950s in research for the U.S. Air Force. In the 1960s, NASA and Air Force developed the material further due to its thermal and oxidative stability, to put it in aerospace and defense. Shortly after its launch in 1983, PBI was used as the outer fabric of the fire suits and hoods.

Properties

Polybenzimidazole is a black polymer, which is entirely made of aromatic monomer units, and has a very high melting point. PBI is firm, hard, resistant to pressure and recovers quickly from the effects of high pressure. Polybenzimidazole has chemically under heavy traffic conditions on good resistance, but is attacked by polar aprotic solvents and at higher temperatures of strong aqueous acids and to a lesser extent of alkalis. Although polybenzimidazole still absorbs a high percentage of water, even at the saturation point, it is stable against hydrolysis. The thermal expansion value similar to that of aluminum.

Applications

Besides the use of PBI fibers in fire protection clothing material as a high-temperature membrane for polymer electrolyte fuel cell (PEFC ) is utilized. This serves as a matrix for phosphoric acid, which ensures the conduction of protons.