What is Nomex | Uses and Properties of Nomex Fiber

What is Nomex?
The first all-aromatic polyamide, which was commercially released by Du Pont in 1961, was Nomex™. Nomex is the trade name of meta aramid fiber. Aromatic polyamide resins which have been developed by Du Pont include the zigzag-linked meta-type is called Nomex. In the meta-aramid fiber Nomex, tensile fatigue occurs in a similar form to that in Nylon. Nomex is made in fiber and fibrid (very short particles) forms. Its main strength is its heat resistance as it does not degenerate until it is subjected to 317ºC – and even then, it does not melt. It can be chemically treated to increase its thermal stability. The metaaramid fiber Nomex is made of poly(m-phenylene terephthalamide). This was produced using the following reaction:

nomex fiber production

Nomex can also be produced as a woven material or as a honeycomb structure. Honeycomb structures are created by fibers mixed with fibrils to make a thin layer of paper. Lines of adhesive are placed on the paper, and then another sheet of paper is placed on top. The process is repeated as needed. The product is then heat cured at a high temperature, and the areas of paper that do not have adhesive on them expand into hexagons. The expanded form is dipped repeatedly in liquid phenolic resin and oven cured until it reaches the required density. The block sheets are then cut into the desired shapes.

nomex fiber
Figure 1: Nomex fiber

The commercial production of Nomex was started in 1965, and this fiber is used for fire-fighting apparel, to allow fire resistance against flame, smoke and high radiation heat. This polyamide fiber is also used for protective garments worn at smelting furnaces or in oil refineries. The heat resistant polymer has a molecular structure that is thermally stable, and stands up to long-term use at temperatures over 300°C.

Properties of Nomex Fiber:

  1. Very high temperature-resistance
  2. High durability
  3. Anti-Static
  4. Shrink-Resistant
  5. Easy care
  6. Comfortable to wear
  7. Resistant to most Industrial oils, solvents and chemicals
  8. Dyes are easily absorbed and fixed into the fabric

Uses of Nomex Fiber:
Hexagonal Nomex—air conditioning units and cushioning that inhibit vibration used in aircrafts, for example. There are other applications, such as aircraft interiors and protective textile, where good textile qualities are required as well as thermal resistance.

nomex fabric
Figure 2: Nomex fabric

Uses for both Nomex and Kevlar:
Paper for electrical insulation in transformers and motors. Nomex is used to create protective clothing for fire-fighters, industrial workers, military aviators, racing drivers, hospital robes, filter bags for pollution control, upholstery fabrics and carpets for aircraft and ships.

Variations:
Variations are numerous and fall into a plethora of categories based on their brightness, color and denier. The variations are indicated by a prefix number e.g. a filament yarns are prefixed with 43 e.g. Type 430 is a bright, off white fiber that weighs two hundred deniers. Spun yarns are prefixed with 45 and are spun similarly to the cotton or worsted system. These are similar to the filaments in terms of brightness, color and denier.

Testing of Aramids:
Rigorous testing is carried out to maintain the safety requirements. Burn tests are carried out on a manikin (called a Thermo-Man) to evaluate the material’s performance under flash-fire conditions for up to ten seconds. During such tests, temperatures can rise to 1,000ºC. The 122 sensors on the Thermo-Man record the temperature on the manikin’s surface, and computers calculate the corporeal damage that would likely occur under such conditions and grade their severity.

References:

  1. Fibres to Fabrics by Bev Ashford
  2. New fibers, 2nd edition by Tatsuya Hongu and Glyn O. Phillips
  3. Physical properties of textile fibres, Fourth edition by W. E. Morton and J. W. S. Hearle
  4. Manufactured Fibre Technology Edited by V.B. Gupta and V.K. Kothari

You may also like:

  1. Synthetic Fibers: Classification, Properties and Applications
  2. Different Types of Man Made Fibers with Their Application
  3. An Overview of Glass Fibre
  4. Nylon: The First Synthetic Fiber
  5. Problems of Man-made Fibers & Methods of Rectification
  6. Acrylic Fiber: Properties, Production Flowchart and Application
  7. Kevlar Fiber: Types, Properties, Manufacturing Process and Applications
  8. Aramid Fibers: Types, Properties, Manufacturing Process and Applications
  9. High Performance Polyethylene Fibers – An Overview
  10. Recent Developments in High Performance Fibers

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