Nomex

Nomex is a flame-resistant meta-aramid material developed in the early 1960s by DuPont and first marketed in 1967.[1]

A firefighter in Toronto, Canada wears a Nomex hood in 2007.

Properties

Nomex and related aramid polymers are related to nylon, but have aromatic backbones, and hence are more rigid and more durable. 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 has less strength: its ultimate tensile strength is 340MPa.[2] However, it has excellent thermal, chemical, and radiation resistance for a polymer material. It can withstand temperatures of up to 370°C.[3]

Production

Nomex is produced by condensation reaction from the monomers m-phenylenediamine and isophthaloyl chloride.[1]

It is sold in both fiber and sheet forms and is used as a fabric where resistance from heat and flame is required. Nomex sheet is actually a calendered paper and made in a similar fashion. Nomex Type 410 paper was the first Nomex paper developed and one of the higher volume grades made, mostly for electrical insulation purposes. Nomex fiber is made in the United States.

Wilfred Sweeny (1926–2011), the DuPont scientist responsible for discoveries leading to Nomex, earned a DuPont Lavoisier Medal[4] in 2002 partly for this work.

Applications

Nomex Paper is used in electrical laminates such as circuit boards and transformer cores as well as fireproof honeycomb structures where it is saturated with a phenolic resin. Honeycomb structures such as these, as well as mylar-Nomex laminates, are used extensively in aircraft construction. Firefighting, military aviation, and vehicle racing industries use Nomex to create clothing and equipment that can withstand intense heat.

A Nomex hood is a common piece of racing and firefighting equipment. It is placed on the head on top of a firefighter's face mask. The hood protects the portions of the head not covered by the helmet and face mask from the intense heat of the fire.

Wildland firefighters wear Nomex shirts and trousers as part of their personal protective equipment during wildfire suppression activities.

Racing car drivers wear driving suits constructed of Nomex and or other fire retardant materials, along with Nomex gloves, long underwear, balaclavas, socks, helmet lining and shoes, to protect them in the event of a fire.

Military pilots and aircrew wear flight suits made of over 92 percent Nomex to protect them from the possibility of cockpit fires and other mishaps. Troops riding in ground vehicles often wear Nomex. Kevlar thread is often used to hold the fabric together at seams.

Military tank drivers also typically use Nomex hoods as protection against fire.[5]

In the U.S. space program, Nomex has been used for the Thermal Micrometeoroid Garment on the Extravehicular Mobility Unit (in conjunction with Kevlar and Gore-Tex) and ACES pressure suit, both for fire and extreme environment (water immersion to near vacuum) protection, and as thermal blankets on the payload bay doors, fuselage, and upper wing surfaces of the Space Shuttle Orbiter. It has also been used for the airbags for the Mars Pathfinder and Mars Exploration Rover missions , the Galileo atmospheric probe, the Cassini-Huygens Titan probe, as an external covering on the AERCam Sprint, and is planned to be incorporated into NASA's upcoming Crew Exploration Vehicle.

Nomex has been used as an acoustic material in Troy, NY, at Rensselaer Polytechnic Institute's Experimental Media and Performing Arts Center (EMPAC) main concert hall. A ceiling canopy of Nomex reflects high and mid frequency sound, providing reverberation, while letting lower frequency sound partially pass through the canopy.[6] According to RPI President Shirley Ann Jackson, EMPAC is the first venue in the world to use Nomex as an architectural material for acoustic reasons.

Nomex (like Kevlar) is also used in the production of loudspeaker drivers.

Honeycomb-structured Nomex paper is used as a spacer between layers of lead in the ATLAS Liquid Argon Calorimeter,[7] and as a laminate core for hull and deck construction in custom boats.[8]

Nomex is used in industrial applications as a filter in exhaust filtration systems, typically a baghouse, that deal with hot gas emissions found in asphalt plants, cement plants, steel smelting facilities, and non-ferrous metal production facilities.[9]

Nomex is used in some classical guitar soundboards in order to create a "composite" top. Nomex's rigidity and low density helps create a clear and loud sound when laminated between cedar and spruce 'skins'. While the 'laminated' technique was created by Matthias Dammann, the use of Nomex within was first employed by luthier Gernot Wagner.

History

The deaths in fiery crashes of race car drivers Fireball Roberts at Charlotte, and Eddie Sachs and Dave MacDonald at Indianapolis in 1964, led to the use of flame-resistant fabrics such as Nomex.[10] In early 1966 Competition Press and Autoweek reported: "During the past season, experimental driving suits were worn by Walt Hansgen, Masten Gregory, Marvin Panch and Group 44's Bob Tullius; these four representing a fairly good cross section in the sport. The goal was to get use-test information on the comfort and laundering characteristics of Nomex. The Chrysler-Plymouth team at the recent Motor Trend 500 at Riverside also wore these suits."[11]

See also

References
  1. Mera, Hiroshi; Takata, Tadahiko (2000). "High-Performance Fibers". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a13_001. ISBN 978-3-527-30673-2.
  2. http://www.matweb.com/search/datasheet_print.aspx?matguid=708a229bb73441b9a9ebc38ad3e44725
  3. Sabir, Tasneem (2018). "Fibers used for high-performance apparel". High-Performance Apparel. pp. 7–32. doi:10.1016/B978-0-08-100904-8.00002-X. ISBN 978-0-08-100904-8.
  4. "Nomex Scientist Earns Lavoisier Medal". FiberSource. June 20, 2002. Archived from the original on January 23, 2013. Retrieved 2008-08-08.
  5. Intense Battles Call for Intense Flash Fire Protection
  6. Immersive Art: Surrounded by Science, Art Flourishes by Michael Eddy, Stage Directions, February 1, 2009
  7. Hervas, L. (2005). "The ATLAS Liquid Argon Electromagnetic Calorimeter: Construction, Commissioning and Selected Test Beam Results". IEEE Transactions on Instrumentation and Measurement. 54 (4): 1505–1512. doi:10.1109/TIM.2005.851233.
  8. Boat Building: Process and Advances, How Core Materials Make Better Boats by Eric W. Sponberg, Naval Architect
  9. http://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/protective-fabrics/uses-and-applications/hot-gas-filtration.html
  10. Competition Press, June 27-July 10, 1964, Page 2.
  11. Competition Press and Autoweek, April 9, 1966, Page 17.
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