Kevlar: trade name aromatic polyamide

Kwolek s task at DuPont was to find a new kind of fiber that was resistant to acids and bases and that would remain stable at high temperatures. In 1964, she discovered such a product, an aromatic polyamide that was five times as strong as steel with half the density of fiberglass. The material was given the name aramid. Aramid was later marketed under the trade names of Kevlar and Nomex . Today, aramid is one of the most widely used substances in polymer matrix composites. 

In theory, almost any polymer can be used as a reinforcement in an advanced composite. By far the most common polymer fiber, however, is aramid, better known by its trade name, Kevlar. Developed originally for use in belted radial tires, aramid is an aromatic polyamide in which benzene fragments (C6H4) alternate with peptide groups (NHC = Q) in forming a polymeric structure ... 

High performance polymer fibers (HPPF) have excellent mechanical properties compared to traditional textile fibers such as nylon. The typical HPPFs are aramid and polyethylene fibers (6). Aramid is a generic name for a class of aromatic polyamide fibers, most of which are varieties of poly(p-pheny-lene terephthalamide). Kevlar is the trade name of the varieties of aramid polymers introduced conunercially by Dupont. The molecules in the fibers of these materials are oriented in the axial direction. Poly(p-phenylene terephthalamide) is a rigid molecule with the following structure ... 

S. L. Kwolek, a woman scientist of DuPont, invented the liquid crystal aromatic polyamides which eventually paved the way to the first commercial liquid crystalline polymer product—poly-p-phenyleneterephthalamide under the trade name Kevlar. She recently recalled, When I dissolved the PBA (poly-p-aminobenzamide) polymer at 10% concentration in tetram-ethylurea with 6.5% LiCl, the solution was unusually fluid, turbid, stir-opalescent, and butter-milk-like in appearance. The fiber that was spun turned out to be extremely strong with a modulus of 430 gpd This discovery in 1964 remains a milestone of this field. In recognition of her contribution, the American Society of Chemistry Industry awarded Kwolek the 1997 Perkin Medal. 

Among the commercially available aramid fibers are Du Font s Nomex (I) and Kelvar (II) in fact these trade names are commonly used in lieu of the generic name. Kelvar 49 is a high-modulus aramid fiber and is the most widely used reinforcing aramid fiber. Kevlar 29 has a lower modulus and Kevlar 149 has a higher modulus than Kevlar 49. Aromatic polyamides are described in greater detail in Chapter 4. 

Another class of fibers that finds application in tires is the aramids. Kevlar is the trade name of the polymer that has found most extensive use among the aramids. Aramid is like nylon in that it contains the amide bond—(CO-NH)—but is produced by copolymerizing terephthalic acid used in polyester and p-phenylenediamine. Hence this aromatic polyamide is termed aramid. 

A lyotropic liquid crystalline aromatic polyamide, sold under the trade name of Kevlar, is available commercially ... 

Aramide fibres. Man-made fibres of aromatic polyamides characterized by high strength, high elastic modulus, good chemical resistance, high thermal stability. Applications tyre cords, protective garments, electric insulators. Trade names Arenka (NL), Kevlar (USA), Nomex (USA). 

Fibers are identified here by their chemical names. In this respect it is useful to know that Twaron and Kevlar are the trade names for PpPTA fibers, and that PRD-49 is a fiber made from PpBA. The para-aromatic polyamide fibers PpPTA, PpBAT and PpBA are often called aramid fibers. 

Polyamide fibers with much higher softening points than nylon 66 or nylon 6 were produced by a team of DuPont chemists who used aromatic reactants instead of the aliphatic reactants used to produce nylon 66. The aramids which were the first liquid crystal polymers, were spun to produce high tenacity fibers which were sold under the trade names of Kevlar and Nomex. 

Recently, high-performance fibres have been developed based on aromatic polyamides, also known as aramids. These are tough enough to be used in rope and cable manufacture, or in protective clothing or body armour. An example of an aromatic polyamide used to make high-strength fibres is poly(p-phenylene terephthalamide), the trade name of which is Kevlar or Twaron ... 

Aramid, or aromatic polyamides, were first introduced in conunercial applications in the early 1960s, with a meta-aramid fiber produced by DuPont under the trade name Nomex. This fiber, which handles similarly to normal textile apparel fibers, is characterized by its excellent resistance to heat, as it neither melts nor ignites in normal levels of oxygen. It is used extensively in the production of protective apparel, air filtration, and thermal and electrical insulation. A para-aramid fiber with much higher tenacity and elastic modulus was also developed in the 1960s-1970s by DuPont, which was the first company to introduce a para-aramid fiber, Kevlar, in 1973. A similar fiber called Twaron with roughly the same chemical structure was introduced by Akzo in 1978. 

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