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Kevlar (para-aramid) [2] is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, [ 3 ] [ 2 ] [ 4 ] the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires.
In 1966, Stephanie Kwolek, a chemist working for E.I. DuPont de Nemours & Co., developed Kevlar; a strong, lightweight liquid polymer that can be spun into a fiber and woven into cloth. [3] Kevlar was initially used as a replacement for steel-belting in tires, and later for use in ropes, gaskets, and automotive and aviation parts.
Terephthaloyl chloride (TCL, 1,4-benzenedicarbonyl chloride) is the acyl chloride of terephthalic acid.It is a white solid at room temperature. It is one of two precursors used to make Kevlar, the other being p-phenylenediamine.
Excellent thermal stability at temperature extremes, water repellency, chemical stability and resistance to petroleum products have made Kevlar KM2 an indispensable asset to the military personnel who use it every day." [1] "Kevlar KM2 fiber is a transversely isotropic material. Its tensile stress–strain response in the axial direction is ...
Nomex is an example of a meta variant of the aramids (Kevlar is a para aramid). Unlike Kevlar, Nomex strands cannot align during filament polymerization and have less strength: its ultimate tensile strength is 340 MPa (49,000 psi). [2] However, it has excellent thermal, chemical, and radiation resistance for a polymer material.
Twaron (a brand name of Teijin Aramid) is a para-aramid, high-performance yarn. [1] It is a heat-resistant fibre, helps in ballistic protection and cut protection. [2] Twaron was developed in the early 1970s by the Dutch company Akzo Nobel's division Enka BV, later Akzo Industrial Fibers.
Delon believed the bond between him and his rescued Belgian Malinois was so strong that the dog would miss him dearly when he died and preferred to spare his pet such pain. (In the end, Delon’s ...
In contrast, Kevlar derives its strength from strong bonding between relatively short molecules. The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers.