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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.
Liquid-crystal polymers are present in melted/liquid or solid form. [7] In solid form, the main example of lyotropic LCPs is the commercial aramid known as Kevlar . The chemical structure of this aramid consists of linearly substituted aromatic rings linked by amide groups.
Both these fluids show the behavior of a non-Newtonian fluid, behaving like a liquid under low or normal pressure and solid under higher pressure or applied fields. The shear thickening fluid is normally made with polyethylene glycol and the solid part is made of nano-particles of silica. This liquid is soaked into all the layers of a Kevlar ...
Let K 0 is the normal conductivity at one bar (10 5 N/m 2) pressure, K e is its conductivity at special pressure and/or length scale. Let d is a plate distance in meters, P is an air pressure in Pascals (N/m 2 ), T is temperature Kelvin, C is this Lasance constant 7.6 ⋅ 10 −5 m ⋅ K/N and PP is the product P ⋅ d/T .
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.
COPVs can be subject to complex modes of failure. In 2016, a SpaceX Falcon 9 rocket exploded on the pad due to the failure of a COPV inside the liquid oxygen tank: [10] the failure resulted from accumulation of frozen solid oxygen between the COPV's aluminum liner and composite overwrap in a void or buckle. The entrapped oxygen can either break ...
The conductive fiber is used for electronic textiles, EMI shielding in woven or knit sheets, or as a braid over wires, and for signal transmission or current conduction. This conductive fiber combines the advantages of Zylon (strength, resistance to high temperatures, durability, lightweight, etc.) with the electrical properties of various metals.
Stephanie Louise Kwolek (/ ˈ k w oʊ l ɛ k /; July 31, 1923 – June 18, 2014) was a Polish-American chemist best known for inventing Kevlar (poly-paraphenylene terephthalamide). ). Her career at the DuPont company spanned more than 40 ye