Editing Kevlar

{{short description|Heat-resistant and strong aromatic polyamide fiber}}
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| Name = Kevlar
| IUPACName = Poly(azanediyl-1,4-phenyleneazanediylterephthaloyl)<ref>{{cite journal |last1=Mormann |first1=Werner |last2=Hellwich |first2=Karl-Heinz |last3=Chen |first3=Jiazhong |last4=Wilks |first4=Edward S. |date=2017 |title=Preferred names of constitutional units for use in structure-based names of polymers (IUPAC Recommendations 2016) |journal=Pure and Applied Chemistry |volume=89 |issue=11 |pages=1695–1736 [1732] |doi=10.1515/pac-2016-0502 |doi-access=free |s2cid=104022755 |s2cid-access=free}}</ref>
| OtherNames =
| ImageFile1 = Kevlar-3D-balls.png
| ImageSize1 = 250px
| ImageName1 = Ball-and-stick model of a single layer of the crystal structure
| ImageFile2 = Aramid fiber2.jpg
| ImageSize2 = 250px
|Section1={{Chembox Identifiers
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| CASNo = 24938-64-5
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = none
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|Section2={{Chembox Properties
| Formula = [-CO-C<sub>6</sub>H<sub>4</sub>-CO-NH-C<sub>6</sub>H<sub>4</sub>-NH-]<sub>n</sub>
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'''Kevlar''' (para-aramid)<ref name=whatiskevlar/> is a strong, heat-resistant [[synthetic fiber]], related to other [[aramid]]s such as [[Nomex]] and [[Technora]]. Developed by [[Stephanie Kwolek]] at [[DuPont]] in 1965,<ref>{{Cite book |doi=10.1002/14356007.a13_001|chapter=High-Performance Fibers|title=Ullmann's Encyclopedia of Industrial Chemistry|year=2000|last1=Mera|first1=Hiroshi|last2=Takata|first2=Tadahiko|isbn=978-3527306732}}</ref><ref name="whatiskevlar"/><ref>{{cite web|url=http://ip.com/pat/US3819587|title=Wholly aromatic carbocyclic polycarbonamide fiber having orientation... - US 3819587 A - IP.com|work=ip.com}}</ref> the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or [[fabric]] sheets that can be used as such, or as an ingredient in [[composite material]] components.

Kevlar has many applications, ranging from bicycle [[tire]]s and [[sailcloth#Kevlar|racing sails]] to [[bulletproof vest]]s, due to its high [[Specific strength|tensile strength-to-weight ratio]]; by this measure it is five times stronger than steel.<ref name=whatiskevlar>{{cite web | url=http://www.dupont.com/kevlar/whatiskevlar.html | title=What is Kevlar | publisher=DuPont | access-date=2007-03-28 | archive-url=https://web.archive.org/web/20070320005408/http://www.dupont.com/kevlar/whatiskevlar.html | archive-date=2007-03-20 | url-status=dead }}</ref> It is also used to make modern marching [[drumhead]]s that withstand high impact, and for [[Mooring|mooring lines]] and other underwater applications.

A similar fiber, [[Twaron]], with the same chemical structure was developed by [[Akzo]] in the 1970s. Commercial production started in 1986, and Twaron is manufactured by [[Teijin Aramid]].<ref>Tatsuya Hongū, Glyn O. Phillips, ''New Fibers'', Ellis Horwood, 1990, p. 22</ref><ref>J. K. Fink, ''Handbook of Engineering and Specialty Thermoplastics: Polyolefins and Styrenics'', Scrivener Publishing, 2010, p. 35</ref>

== History ==
[[File:Stephanie Kwolek Women in Chemistry from video.png|thumb|left|Inventor of Kevlar, [[Stephanie Kwolek]], a Polish-American chemist]]

Poly-paraphenylene terephthalamide (K29) – branded Kevlar – was invented by the Polish-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.<ref name="MIT">{{cite web |title=Inventing Modern America: Insight&nbsp;— Stephanie Kwolek |url=http://web.mit.edu/invent/www/ima/kwolek_bio.html |archive-url=https://web.archive.org/web/20090327141201/http://web.mit.edu/invent/www/ima/kwolek_bio.html | publisher=Lemelson-[[Massachusetts Institute of Technology|MIT]] program |archive-date=March 27, 2009 |url-status=dead |access-date=May 24, 2009}}</ref> The polymers she had been working with, poly-p-phenylene-terephthalate and polybenzamide,<ref name="Bookrags">{{Cite book |title=Stephanie Louise Kwolek Biography |url=http://www.bookrags.com/biography/stephanie-louise-kwolek-woi/ |archive-url=https://web.archive.org/web/20110629171913/http://www.bookrags.com/biography/stephanie-louise-kwolek-woi/ |publisher=Bookrags |archive-date=June 29, 2011 |url-status=live |access-date=May 24, 2009 }}</ref> formed [[liquid crystal]]s in solution, something unique to polymers at the time.<ref name="MIT"/>

The solution was "cloudy, [[opalescent]] upon being stirred, and of low [[viscosity]]" and usually was thrown away. However, Kwolek persuaded the technician, Charles Smullen, who ran the [[Spinneret (polymers)|spinneret]], to test her solution, and was amazed to find that the fiber did not break, unlike [[nylon]]. Her supervisor and her laboratory director understood the significance of her discovery and a new field of [[polymer chemistry]] quickly arose. By 1971, modern Kevlar was introduced.<ref name="MIT" /> However, Kwolek was not very involved in developing the applications of Kevlar.<ref name="American Heritage">{{cite web |first=Jim |last=Quinn|title=I was able to be Creative and work as hard as I wanted|url=http://www.americanheritage.com/articles/magazine/it/2003/3/2003_3_60.shtml |archive-url=https://web.archive.org/web/20081202052507/http://americanheritage.com/articles/magazine/it/2003/3/2003_3_60.shtml |publisher=American Heritage Publishing|archive-date=December 2, 2008 |url-status=dead |access-date=May 24, 2009}}</ref>

In 1971, [[Lester Shubin]], who was then the Director of Science and Technology for the National Institute for Law Enforcement and Criminal Justice,<ref name=PBAS>{{cite book|author=United States Congress Office of Technology Assessment|title=Police Body Armor Standards and Testing, p. 97|publisher=U.S. Govt. Printing Office|date=August 1992|isbn=9781428921368|url=https://books.google.com/books?id=BVgbzZjTkWwC}}</ref> suggested using Kevlar to replace nylon in bullet-proof vests.<ref>{{cite news|author=Corie Lok|title=Life Vest: Lester Shubin and Nicholas Montanarelli turned Kevlar into lifesaving armor|publisher=Technology Review|date=February 2005|url=http://www.technologyreview.com/business/14182/}}</ref>  Prior to the introduction of Kevlar, [[flak jacket]]s 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.<ref>{{Cite news|url=https://www.nytimes.com/2009/12/03/us/03shubin.html|title=Lester Shubin Dies at 84; Used Kevlar in Vests, Saving Lives|newspaper=The New York Times|date=3 December 2009|last1=Martin|first1=Douglas}}</ref><ref name=WSJ>{{cite news|author=Patricia Sullivan|title=Lester D. Shubin, 84: Developed the Kevlar bulletproof vest|newspaper=The Washington Post|date=2009-11-26|url=https://www.washingtonpost.com/wp-dyn/content/article/2009/11/25/AR2009112503917.html}}</ref>{{verify source|date=July 2023}}  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.<ref>{{Cite web|url=https://digital.hagley.org/VID_2011320_B05_ID01|title = Innovation: Agent of Change}}</ref>

== Production ==
[[file:Poly(p-phenylenterephthalamid)-Synthese.svg|thumb|The reaction of 1,4-phenylene-diamine (''para''-phenylenediamine) with terephthaloyl chloride yielding Kevlar]]

Kevlar is [[Chemical synthesis|synthesized]] in solution from the monomers 1,4-[[phenylene]]-di[[amine]] ([[P-Phenylenediamine|''para''-phenylenediamine]]) and [[terephthaloyl chloride]] in a [[Condensation polymer|condensation reaction]] yielding [[hydrochloric acid]] as a byproduct. The result has [[liquid crystal|liquid-crystalline]] behavior, and mechanical drawing orients the polymer chains in the fiber's direction. [[Hexamethylphosphoramide]] (HMPA) was the solvent initially used for the [[polymerization]], but for safety reasons, DuPont replaced it by a solution of ''N''-methyl-pyrrolidone and calcium chloride. As this process had been patented by Akzo (see above) in the production of [[Twaron]], a [[patent war]] ensued.<ref>[http://www.explainthatstuff.com/kevlar.html How Kevlar® works: a simple introduction]. Explainthatstuff.com (2009-12-07). Retrieved on 2012-05-26.</ref>

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 (textiles)|spinning]].<ref>{{Cite web |url=https://www.rrc.ca/academic-news/2013/08/01/chemical-of-the-week-kevlar/ |title=Chemical of the Week: Kevlar |date=2013-08-01 |access-date=2023-09-06 |website=[[Red River College Polytechnic]]}}</ref>

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<ref>{{Cite web|url=http://www.matweb.com/search/datasheettext.aspx?matguid=706f16a3a8be468284571dd36bbdea35|title = DuPont™ Kevlar® 149 Fiber, diam. 12 µm}}</ref><ref>{{cite web| url = https://www.researchgate.net/publication/279740540| title = Determination of Fracture Behavior under Biaxial Loading of Kevlar 149}}</ref>
* ''Kevlar AP'' – 15% higher tensile strength than K-29<ref>[http://www2.dupont.com/Kevlar/en_US/assets/downloads/K23339_KevlarAP.pdf Kevlar K-29 AP Technical Data Sheet] {{Webarchive|url=https://web.archive.org/web/20121018120411/http://www2.dupont.com/Kevlar/en_US/assets/downloads/K23339_KevlarAP.pdf |date=2012-10-18 }} – Dupont</ref>
* ''Kevlar XP'' – lighter weight resin and KM2 plus fiber combination<ref>[http://www2.dupont.com/Kevlar/en_US/products/life_protection/kevlarxp_dupont.html Kevlar XP] {{Webarchive|url=https://web.archive.org/web/20110324183411/http://www2.dupont.com/Kevlar/en_US/products/life_protection/kevlarxp_dupont.html |date=2011-03-24 }} – Dupont</ref>
* ''[[Kevlar KM2]]'' – enhanced ballistic resistance for armor applications<ref>[http://www2.dupont.com/Kevlar/en_US/products/life_protection/kevlar_km2.html Kevlar KM2 Technical Description] {{Webarchive|url=https://web.archive.org/web/20120229045242/http://www2.dupont.com/Kevlar/en_US/products/life_protection/kevlar_km2.html |date=2012-02-29 }}. dupont.com. Retrieved on 2012-05-26.</ref>

The [[Ultraviolet light|ultraviolet]] component of sunlight degrades and decomposes Kevlar, a problem known as ''[[UV degradation]]'', and so it is rarely used outdoors without protection against sunlight.<ref>{{Cite journal|last1=Yousif|first1=Emad|last2=Haddad|first2=Raghad|date=2013-08-23|title=Photodegradation and photostabilization of polymers, especially polystyrene: review|journal=SpringerPlus|volume=2|pages=398|doi=10.1186/2193-1801-2-398|issn=2193-1801|pmc=4320144|pmid=25674392 |doi-access=free }}</ref>

==Structure and properties==
[[Image:Kevlar chemical structure H-bonds.svg|thumb|upright=1.8|Molecular structure of Kevlar: '''bold''' represents a [[monomer]] unit, '''dashed''' lines indicate hydrogen bonds.]]
When Kevlar is [[spinneret (polymers)|spun]], the resulting fiber has a [[tensile strength]] of about [[Pressure|{{cvt|3620|MPa|psi}}]],<ref>{{cite journal | last1 = Quintanilla | first1 = J. | year = 1990 | title = Microstructure and properties of random heterogeneous materials : a review of theoretical results | journal = Polymer Engineering and Science | volume = 39 | issue = 3| pages = 559–585 | doi = 10.1002/pen.11446 }}</ref> and a [[relative density]] of 1.44 (0.052&nbsp;lb/in<sup>3</sup>).  The polymer owes its high strength to the many inter-chain bonds. These inter-molecular [[hydrogen bonds]] form between the carbonyl groups and N''H'' centers.  Additional strength is derived from [[aromatic stacking interaction]]s between adjacent strands. These interactions have a greater influence on Kevlar than the [[Van der Waals bonding|van der Waals]] interactions and chain length that typically influence the properties of other synthetic polymers and fibers such as [[ultra-high-molecular-weight polyethylene]]. The presence of [[Salt (chemistry)|salt]]s and certain other impurities, especially [[calcium]], could interfere with the strand interactions and care is taken to avoid inclusion in its production. Kevlar's structure consists of relatively rigid molecules which tend to form mostly planar sheet-like structures rather like [[silk]] protein.<ref>Michael C. Petty, ''Molecular electronics: from principles to practice'', John Wiley & Sons, 2007, p. 310</ref>

==Thermal properties==
Kevlar maintains its strength and resilience down to cryogenic temperatures ({{cvt|−196|°C|°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 {{cvt|160|°C|°F}} for 500 hours, its strength is reduced by about 10%; and enduring {{cvt|260|°C|°F}} for 70 hours, its strength is reduced by about 50%.<ref>[http://www2.dupont.com/Kevlar/en_US/assets/downloads/KEVLAR_Technical_Guide.pdf KEVLAR Technical Guide] {{Webarchive|url=https://web.archive.org/web/20130527125839/http://www2.dupont.com/Kevlar/en_US/assets/downloads/KEVLAR_Technical_Guide.pdf |date=2013-05-27 }}. dupont.com. Retrieved on 2012-05-26.</ref>

==Applications==
{{More citations needed section|date=March 2015}}

=== Science ===

Kevlar is often used in the field of [[cryogenics]] for its low [[thermal conductivity]] and high strength relative to other materials for [[wiktionary:suspension|suspension]] purposes. It is most often used to suspend a [[paramagnetic]] salt enclosure from a [[superconducting magnet]] mandrel in order to minimize any heat leaks to the paramagnetic material. It is also used as a thermal standoff or structural support where low heat leaks are desired.

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 {{cvt|192|cm|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|date=October 2010}}

=== Protection ===
[[File:Dunham helmet.jpg|thumb|Pieces of a Kevlar helmet used to help absorb the blast of a grenade]]

Kevlar is a well-known component of [[personal armor]] such as [[combat helmet]]s, [[ballistic face mask]]s, and [[ballistic vest]]s. The [[Personnel Armor System for Ground Troops|PASGT helmet and vest]] that were used by [[United States]] military forces used Kevlar as a key component in their construction. Other military uses include bulletproof face masks and [[spall#Antitank warfare|spall liner]]s used to protect the crews of [[armoured fighting vehicle]]s. [[Nimitz-class aircraft carrier|''Nimitz''-class aircraft carriers]] use Kevlar reinforcement in vital areas.  Civilian applications include: high heat resistance uniforms worn by firefighters, body armour worn by police officers, security, and police tactical teams such as [[SWAT]].<ref name="www2.dupont.com">[http://www2.dupont.com/Kevlar/en_US/uses_apps/body_armor/index.html Body Armor Made with Kevlar] {{Webarchive|url=https://web.archive.org/web/20120224094454/http://www2.dupont.com/Kevlar/en_US/uses_apps/body_armor/index.html |date=2012-02-24 }}. (2005-0604). DuPont the Miracles of Science. Retrieved November 4, 2011</ref>

Kevlar is used to manufacture gloves, sleeves, jackets, [[chaps]] and other articles of clothing<ref>[http://www2.dupont.com/Personal_Protection/en_US/products/kevlar/index.html Kevlar – DuPont Personal Protection] {{Webarchive|url=https://web.archive.org/web/20110816162655/http://www2.dupont.com/Personal_Protection/en_US/products/kevlar/index.html |date=2011-08-16 }}. .dupont.com. Retrieved on 2012-05-26.</ref> 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.<ref name="www2.dupont.com"/>

[[File:Kevlar canoe algonquin.JPG|thumb|right|Kevlar is a very popular material for racing canoes.]]

It is used for [[motorcycle safety clothing]], especially in the areas featuring padding such as the shoulders and elbows. In the sport of [[fencing]] it is used in the protective jackets, breeches, plastrons and the bib of the masks. It is increasingly being used in the ''peto'', the padded covering which protects the [[picador]]s' horses in the bullring. [[Speed skating|Speed skaters]] also frequently wear an under-layer of Kevlar fabric to prevent potential wounds from skates in the event of a fall or collision.

=== Sport ===
In ''[[kyudo]]'', or Japanese [[archery]], it may be used for [[bow string]]s, as an alternative to the more expensive<ref>{{Cite web|url=http://www.shuitsukankyudojo.de/publications/downloads/manual.pdf|title=Kyudo – the way of the bow; The art of shooting the traditional Japanese bow according to the Heki Insai Ha School|last=Genzini|first=Luigi}}</ref> [[hemp]]. It is one of the main materials used for [[paraglider]] suspension lines.<ref>{{citation|last=Pagen|first=Dennis|title=Paragliding Flight: Walking on Air|year=1990|publisher=Pagen Books|isbn=978-0-936310-09-1|page=9}}</ref> It is used as an inner lining for some [[bicycle tire]]s to prevent punctures. In [[table tennis]], plies of Kevlar are added to custom ply blades, or paddles, in order to increase bounce and reduce weight. [[Tennis racquets]] are sometimes strung with Kevlar. It is used in sails for high performance racing boats.

In 2013, with advancements in technology, [[Nike, Inc|Nike]] used Kevlar in shoes for the first time. It launched the Elite II Series,<ref name="Nike News">{{cite web|title=Nike Basketball's ELITE Series 2.0 Rises Above the Rest|url=http://news.nike.com/news/nike-basketball-s-superhero-elite-series-2-0-rises-above-the-rest|website=Nike News|access-date=April 16, 2017|date=March 20, 2013}}</ref> with enhancements to its earlier version of [[basketball shoe]]s by using Kevlar in the [[Welt (shoe)|anterior]] as well as the [[shoe lace]]s. This was done to decrease the elasticity of the tip of the shoe in contrast to the nylon conventionally used, as Kevlar expanded by about 1% against nylon which expanded by about 30%. Shoes in this range included LeBron, HyperDunk and Zoom Kobe VII. However these shoes were launched at a price range much higher than average cost of basketball shoes. It was also used in the laces for the [[Adidas]] F50 adiZero Prime football boot.

Several companies, including [[Continental AG]], manufacture cycle tires with Kevlar to protect against punctures.<ref>{{Cite web|url=https://www.continental-tires.com/bicycle/technology/city-trekking/safetysystem-breaker|title=SafetySystem Breaker|website=www.continental-tires.com|access-date=2019-02-25}}</ref>

Folding-bead bicycle tires, introduced to cycling by [[Michelin|The Michelin Elan tire]] in 1975, along with Mavic "Module E" hook-beaded rims, used 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.<ref>[http://www.audioholics.com/reviews/speakers/bookshelf/bw-cm1/cm1-design-and-construction Audio speaker use]. Audioholics.com (2009-07-23). Retrieved on 2012-05-26.</ref> Additionally, Kevlar has been used as a [[strength member]] in fiber optic cables such as the ones used for audio data transmissions.<ref>[http://www2.dupont.com/Kevlar/en_US/index.html Welcome to Kevlar] {{Webarchive|url=https://web.archive.org/web/20110716020609/http://www2.dupont.com/Kevlar/en_US/index.html |date=2011-07-16 }}. (2005-06-04). DuPont the Miracles of Science. Retrieved November 4, 2011</ref>

Kevlar can be used as an acoustic core on bows for [[string instruments]].<ref>[http://www.codabow.com/violin_sx.html Carbon fiber bows for violin, viola, cello and bass] {{webarchive|url=https://web.archive.org/web/20111110194549/http://www.codabow.com/violin_sx.html |date=2011-11-10 }}. CodaBow. Retrieved on 2012-05-26.</ref> Kevlar's physical properties provide strength, flexibility, and stability for the bow's user. To date, the only manufacturer of this type of bow is [[CodaBow]].<ref>[http://www.codabow.com/insidecb_h1.html Carbon fiber bows for violin, viola, cello and bass] {{webarchive|url=https://web.archive.org/web/20120309010559/http://www.codabow.com/insidecb_h1.html |date=2012-03-09 }}. CodaBow. Retrieved on 2012-05-26.</ref>

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.<ref>[http://www.aitchisoncellos.com/articletailpieces.htm Tailpieces and Tailcords] {{webarchive|url=https://web.archive.org/web/20121123022201/http://www.aitchisoncellos.com/articletailpieces.htm |date=2012-11-23 }} Aitchison Mnatzaganian cello makers, restorers and dealers. Retrieved on 2012-12-17.</ref>

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.<ref name="remo_Fala">{{Cite web |title=Falam® Slam |work=Remo |access-date=11 December 2019 |url= https://remo.com/products/product/falam-slam/}}</ref>

Kevlar is used in the [[Woodwind instrument|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.<ref>{{cite web|title=FibraCell Website|url=http://www.fibracelldirect.com/}}</ref>

===Motor vehicles===

Kevlar is sometimes used in structural components of cars, especially high-value performance cars such as the [[Ferrari F40]].<ref>{{Cite web|url = https://www.topgear.com/car-news/classic/story-ferrari-f40-its-creators|title = The story of the Ferrari F40 – by its creators|date = 2017-07-21|access-date = 2019-02-25|archive-date = 2021-06-03|archive-url = https://web.archive.org/web/20210603111551/https://www.topgear.com/car-news/classic/story-ferrari-f40-its-creators|url-status = dead}}</ref>

The chopped fiber has been used as a replacement for asbestos in [[brake pad]]s.<ref>{{Cite news|url=http://www.bikeradar.com/gear/category/components/brake-pads/product/review-superstar-components-kevlar-compound-disc-brake-pads-11-44949/|title=Superstar Kevlar compound disc brake pads review|newspaper=BikeRadar|access-date=2016-10-23|archive-date=2016-10-24|archive-url=https://web.archive.org/web/20161024085504/http://www.bikeradar.com/gear/category/components/brake-pads/product/review-superstar-components-kevlar-compound-disc-brake-pads-11-44949/|url-status=dead}}</ref> Aramids such as Kevlar release less airborne fibres than [[asbestos]] brakes and do not have the carcinogenic properties associated with asbestos.<ref>{{Cite journal|last1=Jaffrey|first1=S.A.M.T|last2=Rood|first2= A.P.|last3=Scott|first3=R.M.|year=1992|title=Fibrous dust release from asbestos substitutes in friction products|url=https://academic.oup.com/annweh/article-abstract/36/2/173/199173?redirectedFrom=PDF|journal=The Annals of Occupational Hygiene|language=en|volume=36|issue=2|pages=173–81|doi=10.1093/annhyg/36.2.173|pmid=1530232|issn=0003-4878}}</ref><ref name="pmid19545198">{{cite journal| author=Donaldson K| title=The inhalation toxicology of p-aramid fibrils. | journal=Crit Rev Toxicol | year= 2009 | volume= 39 | issue= 6 | pages= 487–500 | pmid=19545198 | doi=10.1080/10408440902911861 | pmc= | s2cid=6508943 | url=https://pubmed.ncbi.nlm.nih.gov/19545198  }}</ref>

=== Other uses ===
[[file:Fire Dancing Golden Gate Bridge.jpg|thumb|Fire poi on a beach in [[San Francisco]]]]
[[file:US Navy 111203-N-WJ771-066 Seaman Apprentice Luis Silva repairs a Kevlar mooring line on the forecastle of the forward-deployed amphibious dock lan.jpg|thumb|Kevlar [[mooring line]]]]

Wicks for [[fire dancing]] props are made of composite materials with Kevlar in them. Kevlar by itself does not absorb fuel very well, so it is blended with other materials such as [[fiberglass]] or [[cotton]]. Kevlar's high heat resistance allows the wicks to be reused many times.

Kevlar is sometimes used as a substitute for [[Teflon]] in some non-stick frying pans.<ref>M.Rubinstein, R.H.Colby, ''Polymer Physics'', Oxford University Press, p337</ref>

Kevlar fiber is used in rope and in cable, where the fibers are kept parallel within a [[polyethylene]] sleeve. The cables have been used in [[suspension bridge]]s such as the bridge at [[Aberfeldy, Scotland]]. They have also been used to stabilize cracking concrete cooling towers by circumferential application followed by tensioning to close the cracks. Kevlar is widely used as a protective outer sheath for [[optical fiber cable]], as its strength protects the cable from damage and kinking. When used in this application it is commonly known by the trademarked name Parafil.<ref>{{Cite journal|last=Burgoyne|first=C. J.|date=1987-03-01|title=Structural use of parafil ropes|journal=Construction and Building Materials|volume=1|issue=1|pages=3–13|doi=10.1016/0950-0618(87)90053-5|issn=0950-0618}}</ref>

Kevlar was used by scientists at [[Georgia Institute of Technology]] as a base textile for an experiment in electricity-producing clothing. This was done by weaving [[zinc oxide]] [[nanowire]]s into the fabric. If successful, the new fabric will generate about 80 milliwatts per square meter.<ref>[http://www.sciam.com/podcast/episode.cfm?id=3E0E600F-F7B2-4F1F-DA377027B8FDC443&sc=rss Fabric Produces Electricity As You Wear It]. Scientific American (2008-02-22). Retrieved on 2012-05-26.</ref>

A retractable roof of over {{cvt|60000|sqft|m2}} of Kevlar was a key part of the design of the [[Olympic Stadium, Montreal]] for the [[1976 Summer Olympics]]. It was spectacularly unsuccessful, as it was completed 10 years late and replaced just 10 years later in May 1998 after a series of problems.<ref>{{Structurae|id=20000742|title=Roof of the Montreal Olympic Stadium}}</ref><ref>[http://www.andrewclem.com/Baseball/OlympicStadium.html Clem's Baseball ~ Olympic Stadium]. Andrewclem.com. Retrieved on 2012-05-26.</ref>

Kevlar can be found as a reinforcing layer in [[rubber]] [[bellows]] [[expansion joints]] and rubber [[hose (tubing)|hose]]s, for use in high temperature applications, and for its high strength. It is also found as a braid layer used on the outside of hose assemblies, to add protection against sharp objects.<ref name="Shepherd">{{cite journal|last1=Shepherd|first1=Robert|last2=Stokes|first2=Adam|last3=Nunes|first3=Rui|last4=Whitesides|first4=George|title=Soft Machines That are Resistant to Puncture and That Self Seal|journal=Advanced Materials|date=October 2013|volume=25|issue=46|pages=6709–6713|doi=10.1002/adma.201303175|pmid=24123311|bibcode=2013AdM....25.6709S |s2cid=9251365 |url=https://dash.harvard.edu/bitstream/handle/1/12361265/54726101.pdf?sequence=1}}</ref><ref name="Specialist">{{cite book|editor-last1=Gong|editor-first1=RH|title=Specialist Yarn and Fabric Structures: Developments and Applications|date=2011|publisher=Woodhead Publishing|isbn=9781845697570|page=349|url=https://books.google.com/books?id=H_w2YgEACAAJ}}</ref><ref>{{cite journal|last1=Meyer|first1=Bruce|title=Unaflex adding space, capacity at S.C. plant|journal=Rubber & Plastics News|date=November 9, 2015|url=http://www.rubbernews.com/article/20151109/NEWS/311029979}}</ref>

Some [[cellphone]]s (including the [[Droid RAZR|Motorola RAZR Family]], the [[Droid Maxx|Motorola Droid Maxx]], [[OnePlus 2]] and [[Pocophone F1]]) have a Kevlar backplate, chosen over other materials such as carbon fiber due to its resilience and lack of interference with signal transmission.<ref>[https://www.motorola.com/Consumers/US-EN/Consumer-Product-and-Services/Mobile-Phones/DROID-RAZR-BY-MOTOROLA-US-EN Droid RAZR]. (2011-10-11). Motorola Mobility. Retrieved November 4, 2011</ref>

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.<ref>{{cite journal|last=Wang|first=Jifeng|author2=Norbert Müller |title=Numerical investigation on composite material marine current turbine using CFD|journal=Central European Journal of Engineering|date=December 2011|volume=1|issue=4|pages=334–340|doi=10.2478/s13531-011-0033-6|bibcode=2011CEJE....1..334W|doi-access=free}}</ref>

==Composite materials==
Aramid fibers are widely used for reinforcing composite materials, often in combination with [[carbon fiber]] and [[glass (fiber)|glass fiber]]. The matrix for high performance composites is usually [[epoxy resin]]. Typical applications include [[monocoque]] bodies for [[Formula 1]] cars, helicopter rotor blades, [[tennis]], [[table tennis]], [[badminton]] and [[squash (sport)|squash]] [[racquet|racket]]s, [[kayak]]s, [[cricket bat]]s, and [[field hockey]], [[ice hockey]] and [[lacrosse]] sticks.<ref>Kadolph, Sara J. Anna L. Langford. Textiles, Ninth Edition. Pearson Education, Inc 2002. Upper Saddle River, NJ</ref><ref>{{Cite journal|author1=D. Tanner |author2=J. A. Fitzgerald |author3=B. R. Phillips | year = 1989| title = The Kevlar Story – an Advanced Materials Case Study|journal = [[Angewandte Chemie International Edition in English]]| volume = 28| issue = 5| pages = 649–654| doi = 10.1002/anie.198906491}}</ref><ref>{{Cite journal| author = E. E. Magat| year = 1980| title = Fibers from Extended Chain Aromatic Polyamides, New Fibers and Their Composites| journal = [[Philosophical Transactions of the Royal Society A]]| volume = 294| issue = 1411| pages = 463–472| jstor=36370| doi=10.1098/rsta.1980.0055|bibcode = 1980RSPTA.294..463M | s2cid = 121588983}}</ref><ref>Ronald V. Joven. Manufacturing Kevlar panels by thermo-curing process. Los Andes University, 2007. Bogotá, Colombia.</ref>

Kevlar 149, the strongest fiber and most crystalline in structure, is an alternative in certain parts of aircraft construction.<ref>{{Cite web|title=Kevlar|url=https://www.physics.ncsu.edu/stxm/science/kevlar/kevlar.html|access-date=2020-11-29|website=www.physics.ncsu.edu}}</ref> The wing leading edge is one application, Kevlar being less prone than carbon or glass fiber to break in bird collisions.

==See also==<!-- PLEASE ERESPECT ALPHABETICAL ORDER -->
* [[Innegra S]]
* [[Ultra-high-molecular-weight polyethylene]]
* [[Twaron]]
* [[Vectran]]

==References==
{{Reflist|30em}}

==External links==
{{Commons category|Kevlar}}
* {{Official website|http://www.kevlar.com/ }}
* [http://www.pslc.ws/macrog/aramid.htm Aramids]
* [http://www.matweb.com/search/SpecificMaterial.asp?bassnum=PDUKEV29 Matweb material properties of Kevlar]
* {{US patent|5565264}}
* [http://www.lbl.gov/MicroWorlds/Kevlar/index.html Kevlar] {{Webarchive|url=https://web.archive.org/web/20160303213649/http://www2.lbl.gov/MicroWorlds/Kevlar/index.html |date=2016-03-03 }}
* [http://www.bodyarmornews.com/bullet-proof-vest/ Kevlar in body armor]
* [https://web.archive.org/web/20091103042718/http://web.mst.edu/~wlf/Synthesis/kevlar.html Synthesis of Kevlar]
* [http://www.ngcc.org.uk/DesktopModules/ViewDocument.aspx?DocumentID=1003 Aberfeldy Footbridge over the River Tay] {{Webarchive|url=https://web.archive.org/web/20111002183457/http://www.ngcc.org.uk/DesktopModules/ViewDocument.aspx?DocumentID=1003 |date=2011-10-02 }}
* [https://web.archive.org/web/20110612170300/http://plastics.inwiki.org/Kevlar Kevlar] at Plastics Wiki

{{DuPont}}
{{Fibers}}

[[Category:Organic polymers]]
[[Category:Body armor]]
[[Category:DuPont products]]
[[Category:Synthetic fibers]]
[[Category:Technical fabrics]]
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[[Category:Products introduced in 1965]]
[[Category:American inventions]]