It is used extensively in the production of protective apparel, air filtration, thermal and electrical insulation, as well as a substitute for asbestos. 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. The illustration thus shows a para-aramid.Īromatic polyamides were first introduced in commercial applications in the early 1960s, with a meta-aramid fiber produced by DuPont as HT-1 and then under the trade name Nomex. That is, the attachment points are diametrically opposite each other in para-aramids, and two atoms apart in meta-aramids. Numbering the carbon atoms sequentially around a ring, para-aramids have the linkages attached at positions 1 and 4, while meta-aramids have them at positions 1 and 3. Para-aramids and meta-aramids Īramids are divided into two main types according to where the linkages attach to the rings. In order to meet the FTC definition of an aramid, at least 85% of these linkages must be attached to two aromatic rings. In aramids these rings are connected via amide linkages each comprising a CO group attached to an NH group. Īromatic in the name refers to the presence of aromatic rings of six carbon atoms. The term was introduced in 1972, accepted in 1974 by the Federal Trade Commission of the USA as the name of a generic category of fiber distinct from nylon, and adopted by the International Standards Organisation in 1977. The attachment points on each ring are diametrically opposite each other, meaning this is classed as a para-aramid.Īramid is a shortened form of aromatic polyamide. The rings are attached alternately to either two NH groups or two CO groups. Terminology and chemical structure Structure of Twaron and Kevlar. Aramids have a very high melting point (>500 ☌ (932 ☏))).Ĭommon aramid brand names include Kevlar, Nomex, and Twaron. As a result, a higher proportion of the chemical bond contributes more to fiber strength than in many other synthetic fibers. The chain molecules in the fibers are highly oriented along the fiber axis. They are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in marine cordage, marine hull reinforcement, as an asbestos substitute, and in various lightweight consumer items ranging from phone cases to tennis rackets. Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers.
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