Polybenzimidazole fiber
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PolyBenzImidazole or PBI fiber (1983) is a synthetic fiber with an extremely high melting point that also does not ignite. Because of its exceptional thermal and chemical stability, it is often used by fire departments and space agencies.
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[edit] PBI's Inventor - “Speed”
PBI fiber was invented by Carl Shipp “Speed” Marvel, (1894.Sept.11-1988.Jan.04).
During World War II, Marvel worked for the National Defense Research Committee to create synthetic rubber, and the efforts of the group that he spear-headed were crowned by success within one year’s time (perhaps so soon because Marvel had so much fun as a chemist and because he was so good at what he did, having earned the reputation of working more than 3 times faster than other synthetic fiber chemists).
In the latter portion of his career, Marvel became interested in the problem of creating high-temperature stable polymers and his investigations carried out under the sponsorship of the U.S.D.A., the U.S.Army, and finally, the U.S.Air Force bore fruit with the synthesis of PolyBenzImidazole that was found to have significant applications to national defense as well as to everyday living. PolyBenzImidazole is as useful to the fabrication of spacesuits as it is to the manufacture of oven mitts. In 1986 (aged 92), Carl Marvel’s many (74) years of faithful and productive service to his profession and to his country were rewarded when President Ronald Reagan presented the National Medal of Science to him in the East Room of the White House. Marvel died on 4 January 1988.
[edit] 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
Current european PBI powder producer: HOS-Technik [1]
[edit] PBI fiber characteristics
The chemical formula of Poly[2,2’-(m-phenylen)-5,5’ bibenzimidazol] (PBI) is believed to be: ([NH-C=CH-C=CH-CH=C-N=C-]2-[C=CH-C=CH-CH=CH-])n OR (C20N4H12)n of Molar mass 308.33608 ± 0.01764 g/mol.
[edit] Chemical Resistance
| Chemical Resistance | Grade |
|---|---|
| Acids - concentrated | Poor |
| Acids - dilute | Fair-Poor |
| Alcohols | Good |
| Alkalis | Good-Poor |
| Aromatic hydrocarbons | Good |
| Greases and Oils | Good |
| Halogenated Hydrocarbons | Good |
| Ketones | Good |
| Chemical Resistance | Grade |
- dyeable to dark shades with basic dyes following caustic pretreatment
- resistant to most chemicals
[edit] Electrical Properties
| Electrical | Properties |
|---|---|
| Dielectric constant @ 1 MHz | 3.2 |
| Dielectric strength | 21 kV·mm-1 |
| Volume resistivity | 8x1014 Ω·cm |
| Electrical | Properties |
- low electrical conductivity and low static electricity buildup
[edit] Mechanical Properties
| Mechanical | Properties |
|---|---|
| Coefficient of friction | 0.19-0.27 |
| Compressive modulus | 6.2 GPa |
| Compressive strength | 400 MPa |
| Elongation at break | 3% |
| Hardness - Rockwell | K115 |
| Izod impact strength | 590 J·m-1 unnotched |
| Poisson's ratio | 0.34 |
| Tensile modulus | 5.9 GPa |
| Tensile strength | 160 MPa |
| Mechanical | Properties |
- abrasion resistant
[edit] Physical Properties
| Physical | Properties |
|---|---|
| Char Yield (under pyrolysis) | High |
| Density | 1.3 g/cm³ |
| Flammability | Does not burn |
| Limiting oxygen index | 58% |
| Radiation resistance | Good |
| Water absorption - over 24 hours | 0.4% |
| Physical | Properties |
- will not ignite or smolder (burn slowly without flame)
- mildew and age resistant
- resistant to sparks and welding spatter
[edit] Thermal Properties
| Thermal | Properties | Grade |
|---|---|---|
| Coefficient of thermal expansion | 23×10-6·K-1 | Low |
| Heat-deflection temperature - 0.45 MPa | 435 °C (815 °F) | High |
| Thermal conductivity @ 23 °C (73.4 °F) | 0.41 W·m-1·K-1 | Low |
| Upper working temperature | 260-400 °C (500-752 °F) | High |
| Thermal | Properties | Grade |
- continuous temperature: 540 °C (1,000 °F)
- melting temperature: 760 °C (1,400 °F) under pyrolysis
- retains fiber integrity and suppleness up to 540 °C (1,000 °F)
[edit] 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 driver suits
- braided packings
- aircraft wall fabrics
[edit] Future Industrial PBI Fiber Uses
[edit] See also
[edit] References
Polybenzimidazole (PBI) - Material Information
Summary of Polybenzimidazole
