Kevlar
Names | |
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IUPAC name
Poly(azanediyl-1,4-phenyleneazanediylterephthaloyl)[1]
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Identifiers | |
ChemSpider |
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Properties | |
[-CO-C6H4-CO-NH-C6H4-NH-]n | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Kevlar (para-aramid)
Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests, all due to its high tensile strength-to-weight ratio; by this measure it is five times stronger than steel.[2] It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications.
A similar fiber called
History
Poly-paraphenylene terephthalamide (K29) – branded Kevlar – was invented by the American chemist Stephanie Kwolek while working for DuPont, in anticipation of a gasoline shortage. In 1964, her group began searching for a new lightweight strong fiber to use for light, but strong, tires.[7] The polymers she had been working with at the time, poly-p-phenylene-terephthalate and polybenzamide,[8] formed liquid crystals while in solution, something unique to those polymers at the time.[7]
The solution was "cloudy,
In 1971, Lester Shubin, who was then the Director of Science and Technology for the National Institute for Law Enforcement and Criminal Justice,[10] suggested using Kevlar to replace nylon in bullet-proof vests.[11] Prior to the introduction of Kevlar, flak jackets made of nylon had provided much more limited protection to users. Shubin later recalled how the idea developed: "We folded it over a couple of times and shot at it. The bullets didn't go through." In tests, they strapped Kevlar onto anesthetized goats and shot at their hearts, spinal cords, livers and lungs. They monitored the goats' heart rate and blood gas levels to check for lung injuries. After 24 hours, one goat died and the others had wounds that were not life threatening.[12][13][verification needed] Shubin received a $5 million grant to research the use of the fabric in bullet-proof vests.
Kevlar 149 was invented by Jacob Lahijani of Dupont in the 1980s.[14]
Production
Kevlar is
Kevlar production is expensive because of the difficulties arising from using concentrated sulfuric acid, needed to keep the water-insoluble polymer in solution during its synthesis and spinning.[16]
Several grades of Kevlar are available:
- Kevlar K-29 – in industrial applications, such as cables, asbestos replacement, tires, and brake linings.
- Kevlar K49 – high modulus used in cable and rope products.
- Kevlar K100 – colored version of Kevlar
- Kevlar K119 – higher-elongation, flexible and more fatigue resistant
- Kevlar K129 – higher tenacity for ballistic applications
- Kevlar K149 – highest tenacity for ballistic, armor, and aerospace applications[17][18]
- Kevlar AP – 15% higher tensile strength than K-29[19]
- Kevlar XP – lighter weight resin and KM2 plus fiber combination[20]
- Kevlar KM2 – enhanced ballistic resistance for armor applications[21]
The
Structure and properties
When Kevlar is
Thermal properties
Kevlar maintains its strength and resilience down to cryogenic temperatures (−196 °C (−320.8 °F)): in fact, it is slightly stronger at low temperatures. At higher temperatures the tensile strength is immediately reduced by about 10–20%, and after some hours the strength progressively reduces further. For example: enduring 160 °C (320 °F) for 500 hours, its strength is reduced by about 10%; and enduring 260 °C (500 °F) for 70 hours, its strength is reduced by about 50%.[25]
Applications
This section needs additional citations for verification. (March 2015) |
Science
Kevlar is often used in the field of
A thin Kevlar window has been used by the NA48 experiment at CERN to separate a vacuum vessel from a vessel at nearly atmospheric pressure, both 192 cm (76 in) in diameter. The window has provided vacuum tightness combined with reasonably small amount of material (only 0.3% to 0.4% of radiation length).[citation needed]
Protection
Kevlar is a well-known component of
Kevlar is used to manufacture gloves, sleeves, jackets, chaps and other articles of clothing[27] designed to protect users from cuts, abrasions and heat. Kevlar-based protective gear is often considerably lighter and thinner than equivalent gear made of more traditional materials.[26]
It is used for
Sport
In
In 2013, with advancements in technology,
Several companies, including Continental AG, manufacture cycle tires with Kevlar to protect against punctures.[31]
Folding-bead bicycle tires, introduced to cycling by Tom Ritchey in 1984,[32][circular reference] use Kevlar as a bead in place of steel for weight reduction and strength. A side effect of the folding bead is a reduction in shelf and floor space needed to display cycle tires in a retail environment, as they are folded and placed in small boxes.
Music
Kevlar has also been found to have useful acoustic properties for loudspeaker cones, specifically for bass and mid range drive units.[33] Additionally, Kevlar has been used as a strength member in fiber optic cables such as the ones used for audio data transmissions.[34]
Kevlar can be used as an acoustic core on bows for
Kevlar is also presently used as a material for tailcords (a.k.a. tailpiece adjusters), which connect the tailpiece to the endpin of bowed string instruments.[37]
Kevlar is sometimes used as a material on marching snare drums. It allows for an extremely high amount of tension, resulting in a cleaner sound. There is usually a resin poured onto the Kevlar to make the head airtight, and a nylon top layer to provide a flat striking surface. This is one of the primary types of marching snare drum heads. Remo's Falam Slam patch is made with Kevlar and is used to reinforce bass drum heads where the beater strikes.[38]
Kevlar is used in the woodwind reeds of Fibracell. The material of these reeds is a composite of aerospace materials designed to duplicate the way nature constructs cane reed. Very stiff but sound absorbing Kevlar fibers are suspended in a lightweight resin formulation.[39]
Motor vehicles
Kevlar is sometimes used in structural components of cars, especially high-value performance cars such as the Ferrari F40.[40]
The chopped fiber has been used as a replacement for asbestos in brake pads.[41] Aramids such as Kevlar release less airborne fibres than asbestos brakes and do not have the carcinogenic properties associated with asbestos.[42][43]
Other uses
Wicks for
Kevlar is sometimes used as a substitute for
Kevlar fiber is used in rope and in cable, where the fibers are kept parallel within a
Kevlar was used by scientists at
A retractable roof of over 60,000 sq ft (5,600 m2) of Kevlar was a key part of the design of the
Kevlar can be found as a reinforcing layer in
Some
The Kevlar fiber/epoxy matrix composite materials can be used in marine current turbines (MCT) or wind turbines due to their high specific strength and light weight compared to other fibers.[53]
Composite materials
Aramid fibers are widely used for reinforcing composite materials, often in combination with
Kevlar 149, the strongest fiber and most crystalline in structure, is an alternative in certain parts of aircraft construction.[58] The wing leading edge is one application, Kevlar being less prone than carbon or glass fiber to break in bird collisions.
See also
References
- S2CID 104022755.
- ^ a b c "What is Kevlar". DuPont. Archived from the original on 2007-03-20. Retrieved 2007-03-28.
- ISBN 978-3527306732.
- ^ "Wholly aromatic carbocyclic polycarbonamide fiber having orientation... - US 3819587 A - IP.com". ip.com.
- ^ Tatsuya Hongū, Glyn O. Phillips, New Fibers, Ellis Horwood, 1990, p. 22
- ^ J. K. Fink, Handbook of Engineering and Specialty Thermoplastics: Polyolefins and Styrenics, Scrivener Publishing, 2010, p. 35
- ^ a b c "Inventing Modern America: Insight — Stephanie Kwolek". Lemelson-MIT program. Archived from the original on March 27, 2009. Retrieved May 24, 2009.
- ^ Stephanie Louise Kwolek Biography. Bookrags. Archived from the original on June 29, 2011. Retrieved May 24, 2009.
- ^ Quinn, Jim. "I was able to be Creative and work as hard as I wanted". American Heritage Publishing. Archived from the original on December 2, 2008. Retrieved May 24, 2009.
- ISBN 9781428921368.
- ^ Corie Lok (February 2005). "Life Vest: Lester Shubin and Nicholas Montanarelli turned Kevlar into lifesaving armor". Technology Review.
- ^ Martin, Douglas (3 December 2009). "Lester Shubin Dies at 84; Used Kevlar in Vests, Saving Lives". The New York Times.
- ^ Patricia Sullivan (2009-11-26). "Lester D. Shubin, 84: Developed the Kevlar bulletproof vest". The Washington Post.
- ^ "Innovation: Agent of Change".
- ^ How Kevlar® works: a simple introduction. Explainthatstuff.com (2009-12-07). Retrieved on 2012-05-26.
- ^ "Chemical of the Week: Kevlar". Red River College Polytechnic. 2013-08-01. Retrieved 2023-09-06.
- ^ "DuPont™ Kevlar® 149 Fiber, diam. 12 µm".
- ^ "Determination of Fracture Behavior under Biaxial Loading of Kevlar 149".
- ^ Kevlar K-29 AP Technical Data Sheet Archived 2012-10-18 at the Wayback Machine – Dupont
- ^ Kevlar XP Archived 2011-03-24 at the Wayback Machine – Dupont
- ^ Kevlar KM2 Technical Description Archived 2012-02-29 at the Wayback Machine. dupont.com. Retrieved on 2012-05-26.
- PMID 25674392.
- .
- ^ Michael C. Petty, Molecular electronics: from principles to practice, John Wiley & Sons, 2007, p. 310
- ^ KEVLAR Technical Guide Archived 2013-05-27 at the Wayback Machine. dupont.com. Retrieved on 2012-05-26.
- ^ a b Body Armor Made with Kevlar Archived 2012-02-24 at the Wayback Machine. (2005-0604). DuPont the Miracles of Science. Retrieved November 4, 2011
- ^ Kevlar – DuPont Personal Protection. .dupont.com. Retrieved on 2012-05-26.
- ^ Genzini, Luigi. "Kyudo – the way of the bow ; The art of shooting the traditional Japanese bow according to the Heki Insai Ha School" (PDF).
- ISBN 978-0-936310-09-1
- ^ "Nike Basketball's ELITE Series 2.0 Rises Above the Rest". Nike News. March 20, 2013. Retrieved April 16, 2017.
- ^ "SafetySystem Breaker". www.continental-tires.com. Retrieved 2019-02-25.
- ^ Tom Ritchey
- ^ Audio speaker use. Audioholics.com (2009-07-23). Retrieved on 2012-05-26.
- ^ Welcome to Kevlar Archived 2011-07-16 at the Wayback Machine. (2005-06-04). DuPont the Miracles of Science. Retrieved November 4, 2011
- ^ Carbon fiber bows for violin, viola, cello and bass Archived 2011-11-10 at the Wayback Machine. CodaBow. Retrieved on 2012-05-26.
- ^ Carbon fiber bows for violin, viola, cello and bass Archived 2012-03-09 at the Wayback Machine. CodaBow. Retrieved on 2012-05-26.
- ^ Tailpieces and Tailcords Archived 2012-11-23 at the Wayback Machine Aitchison Mnatzaganian cello makers, restorers and dealers. Retrieved on 2012-12-17.
- ^ "Falam® Slam". Remo. Retrieved 11 December 2019.
- ^ "FibraCell Website".
- ^ "The story of the Ferrari F40 – by its creators". 2017-07-21. Archived from the original on 2021-06-03. Retrieved 2019-02-25.
- ^ "Superstar Kevlar compound disc brake pads review". BikeRadar. Archived from the original on 2016-10-24. Retrieved 2016-10-23.
- PMID 1530232.
- S2CID 6508943.
- ^ M.Rubinstein, R.H.Colby, Polymer Physics, Oxford University Press, p337
- ISSN 0950-0618.
- ^ Fabric Produces Electricity As You Wear It. Scientific American (2008-02-22). Retrieved on 2012-05-26.
- ^ Roof of the Montreal Olympic Stadium at Structurae
- ^ Clem's Baseball ~ Olympic Stadium. Andrewclem.com. Retrieved on 2012-05-26.
- S2CID 9251365.
- ISBN 9781845697570.
- ^ Meyer, Bruce (November 9, 2015). "Unaflex adding space, capacity at S.C. plant". Rubber & Plastics News.
- ^ Droid RAZR. (2011-10-11). Motorola Mobility. Retrieved November 4, 2011
- .
- ^ Kadolph, Sara J. Anna L. Langford. Textiles, Ninth Edition. Pearson Education, Inc 2002. Upper Saddle River, NJ
- .
- S2CID 121588983.
- ^ Ronald V. Joven. Manufacturing Kevlar panels by thermo-curing process. Los Andes University, 2007. Bogotá, Colombia.
- ^ "Kevlar". www.physics.ncsu.edu. Retrieved 2020-11-29.
External links
- Official website
- Aramids
- Matweb material properties of Kevlar
- U.S. patent 5,565,264
- Kevlar Archived 2016-03-03 at the Wayback Machine
- Kevlar in body armor
- Synthesis of Kevlar
- Aberfeldy Footbridge over the River Tay Archived 2011-10-02 at the Wayback Machine
- Kevlar at Plastics Wiki