Aramid
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Aramid fiber (1961) is a fire-resistant and strong synthetic fiber. It is used in aerospace and military applications, for "bullet-proof" body armor fabric, and as an asbestos substitute. The term is a shortened form of "aromatic polyamide".
A well-known type of aramid fiber (a para-aramid nylon) is commonly known by its DuPont trade name, Kevlar, or Teijin trade name Twaron. It was developed by Stephanie Kwolek. An especially fireproof meta variant is Nomex.
Aramid fiber characteristics
- sensitive to degradation from ultraviolet radiation
- good resistance to abrasion, organic solvents, and thermal degradation
- sensitive to moisture and salts
- nonconductive
- no melting point
- low flammability
- good fabric integrity at elevated temperatures
- para-aramid fibers such as Kevlar and Twaron, which have a slightly different molecular structure, also provide outstanding strength-to-weight properties, and have high tenacity, and high Young's modulus.
- difficult to dye - usually solution dyed [1]
- prone to static build-up unless finished [1]
Major industrial uses
- flame-resistant clothing
- protective clothing and helmets
- body armor, although it is being surpassed by stronger ultra-high molecular weight polyethylene products such as Dyneema and Spectra.
- composite materials
- asbestos replacement
- hot air filtration fabrics
- tire and mechanical rubber goods reinforcement
- ropes and cables
- sail cloth (not necessarily racing boat sails)
- sporting goods
- drumheads
- speaker woofers
- Boathull material
Production
The Federal Trade Commission definition for Aramid fiber is "A manufactured fiber in which the fiber-forming substance is a long-chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to two aromatic rings."
Aramid fiber is produced by spinning a solid fiber from a liquid chemical blend. This relies on a co-solvent with an ionic component (calcium chloride) to occupy the hydrogen bonds of the amide groups, and an organic solvent (N-methyl pyrrolinidone) to dissolve the aromatic polymer; prior to DuPont's (Kwolek's) invention of this process, no practical means of dissolving the polymer was known.
Aramid fibers are either round or dog bone in shape.
First U.S. Commercial Aramid Fiber Production: 1961, DuPont Company.
Current U.S. Aramid Fiber Producers: DuPont Company
See also
References
[1] Kadolph, Sara J. Anna L. Langford. Textiles, Ninth Edition. Pearson Education, Inc 2002. Upper Sadddle River, NJ
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