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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.
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 ...
In 1973, DuPont was the first company to introduce a para-aramid fiber, calling it Kevlar; this remains one of the best-known [citation needed] para-aramids and/or aramids. In 1978, Akzo introduced a similar fiber with roughly the same chemical structure calling it Twaron .
In the 1980s, Dr. Jacob Lahijani, Senior Chemist at DuPont, invented Kevlar 149 and was highlighted in the "Innovation: Agent of Change. [78] Kevlar 149 is used in armor, belts, hoses, composite structures, cable sheathing, gaskets, brake pads, clutch linings, friction pads, slot insulation, phase barrier insulation, and interturn insulation. [79]
This is a list of prices of chemical elements. Listed here are mainly average market prices for bulk trade of commodities. Listed here are mainly average market prices for bulk trade of commodities. Data on elements' abundance in Earth's crust is added for comparison.
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.
Liquid armour is a material under research by defense institutions and universities around the world including the United States Army Research Laboratory (ARL). [1] [2] [3] Some of the earliest research in this area was performed at Massachusetts Institute of Technology [4] and University of Delaware [5] in 2003.
Although the tensile strength is similar to Kevlar, Vectran still tends to experience tensile fractures when exposed to significant stress.The wispy, hair-like fibers tend to fray, to easily acquire dirt, and to readily entangle in hook-and-loop fasteners, from which they must sometimes then be cut or (when possible) torn. [2]