Polybenzimidazole

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PolyBenzImidazole or PBI fiber (1983) is a synthetic fiber with no melting point that also does not ignite. Due to its exceptional thermal and chemical stability, it is often used by fire departments and space agencies.

PBI fiber characteristics

• continuous temperature: 1,000°F (540°C)
• melting temperature: 1,400°F (760°C)
• no melting point (in flame tests)
• will not ignite or smolder
• retains fiber integrity and suppleness up to 1,000°F
• low shrinkage and high strength retention when exposed to high temperature
• high char yield
• dyeable to dark shades with basic dyes following caustic pretreatment
• mildew and age resistant
• abrasion resistant
• low thermal conductivity
• resistant to most chemicals
• low electrical conductivity and low static electricity buildup
• resistant to sparks and welding spatter

Major Industrial PBI Fiber Uses

• high-performance protective apparel such as:
  • firefighter turnout coats and suits
  • astronaut space suits
  • high temperature protective gloves
  • welders' apparel
  • race car driver suits
• braided packings
• aircraft wall fabrics

Production

The Federal Trade Commission definition for PBI fiber is "A manufactured fiber in which the fiber-forming substance is a long chain aromatic polymer having recurring imidazole groups as an integral part of the polymer chain."

PBI is prepared by step-growth polymerization from tetra-aminobiphenyl and diphenyl isophthalate spun via a dry spinning process using dimethyl acetamide as the solvent.

First U.S. Commercial PBI Fiber Production: 1983, Celanese Corporation

Current U.S. PBI Fiber Producers: Celanese Corporation