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Kevlar vs Nomex

Views:54     Author:Site Editor     Publish Time: 2021-01-15      Origin:Site


Kevlar and Nomex are two new-tech fibers with great heat resistance. The structures of them are very similar, as they both belong to Aramid fibers. However, there are still some differences that make a big gap between their properties. And this article is going to figure it out from the following aspects.


What is Aramid fiber?

Aramid fiber is a kind of man-made fiber with high performance. The term 'aramid' is short for 'aromatic polyamide', which was first introduced into commercial applications in the early 1960s. There are four different types of fibers based on chemical structural properties. Kevlar and Nomex are two well-known fibers that stand for para-aramids and meta-aramids respectively. When it comes to other common aramid brand names, including Twaron, Technora, Heracron, and more. 

 

Introduction of Nomex & Kevlar

Nomex is a kind of meta-aramid fiber. It was developed in the early 1960s by DuPont and first marketed in 1967. While Kevlar, a para-aramid material, came out a little later than Nomex. It was first introduced by Dupont in 1965 and has been available on the market since the early 1970s. As time goes on, it has become the best known of all aramid composites now. 

Kevlar felt belt & Nomex felt belt

Kevlar felt belt & Nomex felt belt

Property


Fireproof

Kevlar and Nomex both have excellent flame resistance with LOI greater than 28%. Limiting oxygen index(LOI) is a standard to determine how easily a material will burn when in contact with a flame. 

 

  • LOI < 22% - flammable

  • LOI: 22% ~ 27% - combustible 

  • LOI >27% - refractory

 

Although they burn in the flame, they stop burning as soon as they are away from the heat source. That means they both are flame retardant by nature. When exposed to fire, they have no melting point and no molten droplets or toxic gases. And the surface of fiber thickens to enhance sealing with no breakage. In other words, it has good fabric integrity at high temperatures. 


More important is that the thick weave structure of synthetic fibers is a very poor thermal conductor. As a result, they are very suitable for firefighter uniforms, safety clothing, and other personal protective equipment(PPE). They can provide more time for the wearer to get away from the flames and out of danger, better protecting their safety.



Heat-resistant

As for the highest temperature, Kevlar can withstand up to 600℃, while Nomex can only resist 370℃. However, the working temperature is always much lower than the above figures to ensure good function. Take the industrial felt belt as an example. Kevlar felt belt is applied in the high-temp zone of 480℃. And Nomex felt belt is for the middle-temp zone of about 280℃. In short, Nomex is not as good as Kevlar in terms of heat resistance. But it is still an ideal cost-saving option, as long as it is properly applied according to its features.

 



With over 18 years of experience, Calm is one of the top suppliers of heat-resistant felt products in China. We always consist of offering affordable and high quality felt products for aluminum extrusion production. Our customers come from all over the world, and they highly approve of our products and services. If you want more information or a quick quote, please feel free to send a message to toby@gdcalm.com. We will get back to you as soon as possible!

 


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