Kevlar

Science

Kevlar is often used in the field of cryogenics for its low thermal conductivity and high strength relative to other materials for 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 192 cm in diameter. The window has provided vacuum tightness combined with reasonably small amount of material (only 0.3% to 0.4% of radiation length).[26]

Protection

Kevlar is a well-known component of personal armor such as combat helmets, ballistic face masks, and ballistic vests. The PASGT helmet and vest that were used by United States military forces relied on Kevlar as a key component in their construction. Other military uses include bulletproof face masks and spall liners used to protect the crews of armoured fighting vehicles. Nimitz-class aircraft carriers use Kevlar reinforcement in vital areas. Civilian applications include high heat resistance uniforms worn by firefighters and body armour worn by police officers, security, and police tactical teams such as SWAT.[27]

Kevlar is used in gloves, sleeves, jackets, chaps and other articles of clothing[28] 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.[27]

It is used in 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 that protects picadors' horses in the bullring. 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 strings, as an alternative to the more expensive[29] hemp. It is one of the main materials used for paraglider suspension lines.[30] It is used as an inner lining for some bicycle tires 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 used Kevlar in shoes for the first time. It launched the Elite II Series,[31] with enhancements to its earlier version of basketball shoes by using Kevlar in the anterior as well as the shoe laces. 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.[32]

Folding-bead bicycle tires, introduced to cycling by 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.[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 string instruments.[35] 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.[36]

Kevlar is also presently used as a material for tailcords (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 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.[44]

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 bridges 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.[45]

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 nanowires into the fabric. If successful, the new fabric will generate about 80 milliwatts per square meter.[46]

A retractable roof of over 60000 sqft 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.[47][48]

Kevlar can be found as a reinforcing layer in rubber bellows expansion joints and rubber hoses, 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.[49][50][51]

Some cellphones (including the Motorola RAZR Family, the 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.[52]

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]