Publish Time: 2021-01-15 Origin: Site
Kevlar and Nomex are two brand new innovations in technology within the fiber world. These unique fibers offer great heat resistance and versatility for many applications, potentially making them a valuable option to consider. However, the structures of both Kevlar and Nomex are very similar, since they both belong to the category of fibers known as “Aramid fibers.” Nevertheless, there are still several notable differences between these two materials. Naturally, these can make a big gap between their properties, which could impact their suitability for your project. With this thought in mind, today, we’re looking at some of the key things you need to know about Kevlar and Nomex and how they differ to find the ideal solution for your needs.
Before we go any further, we first need to consider what Aramid fibers are and their key properties. Typically, an Aramid fiber is a type of man-made fiber material that provides exceptionally high levels of performance. The term ‘Aramid’ is short for ‘aromatic polyamide,’ and this was first introduced into commercial applications in the early 1960s. Since then, they have both become widely popular for many applications.
There are four types of Aramid fibers, which differ based on their chemical and structural properties. Kevlar and Nomex are two of the most well-known fibers; these represent para-aramids and meta-aramids, respectively. Moreover, there are several other common aramid brands on the market, including Twaron, Technora, Heracron, and several more.
Introduction of Nomex & Kevlar
Nomex is a type of meta-aramid fiber. It was developed in the early 1960s by DuPont and first marketed for commercial use in 1967. Meanwhile, Kevlar, a para-aramid material, came out a little later than Nomex. It was again invented and manufactured by the fiber experts at Dupont, but it came out in 1965. It has been available on the market since the early 1970s. Of the two, as time goes by, the latter has generally become the better-known of all aramid composites, despite the similarities.
Kevlar felt belt & Nomex felt belt
When choosing between Kevlar and Nomex materials, considering the different properties of each is understandably crucial. However, if this is something that’s left you feeling a little unsure, we’ve outlined a few key features as follows to help inform your decision.
Fireproof
Kevlar and Nomex both have excellent flame resistance with an LOI of greater than 28%. The limiting oxygen index (LOI) is an industry-standard measure that is used to determine how easily a material will burn when in contact with an open flame. This directly relates to its ease of catching alight, which translates to superior or lesser fire resistance and fire safety accordingly.
● LOI < 22% - flammable
● LOI 22% ~ 27% - combustible
● LOI >27% - refractory
Although both materials will 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, and their LOI score classifies them as “refractory.” Moreover, when exposed to flames, they have no melting point and produce no molten droplets or toxic gases. Furthermore, the surface of the fiber thickens to enhance sealing with no breakage. In other words, it has excellent fabric integrity, even at high temperatures.
More important is that the thick weave structure of synthetic fibers makes them a very poor thermal conductor. As a result, they are highly suitable for firefighter uniforms, safety clothing, and other personal protective equipment (PPE). They can provide the wearer with more time to escape from the flames and get to a location that’s away from danger, better protecting their safety and reducing the risk of injuries associated with fires.
Heat-Resistant
When we consider the highest temperature tolerated by each material, Kevlar can withstand up to 600℃. Contrastingly, Nomex can only resist 370℃, making it substantially less temperature resistant overall. However, the working temperature should always be kept significantly lower than the above figures to ensure good function.
Let’s consider our industrial felt belt as an example. Kevlar felt belt is applied in the high-temp zone of 480℃, and Nomex felt belts are more suitable for the middle-temp zone of about 280℃.
In short, Nomex is not as effective as Kevlar in terms of heat resistance. Nevertheless, it is still an ideal cost-saving option for lower temperature applications, so long as it is properly applied according to its features.
Water Resistance
While Kevlar is generally considered the superior material over Nomex, there is one area in which Nomex excels particularly: its water resistance. While Kevlar does not typically provide overly good water resistance, Nomex is excellent for repelling water thanks to its strong, tightly woven structure. Since the compounds in Nomex materials also won’t react with water, it’s achieved an impressive score of 90 on the AATCC 22 measure, which makes it excellent for applications requiring high temperature water handling. Moreover, it’s worth considering that this makes Nomex incredibly easy to maintain while reducing the risk of spills and damage from water, etc. By contrast, Kevlar’s properties do not readily lend themselves to water management and handling applications.
With over 18 years of experience, Calm is one of China’s top heat-resistant felt products and materials suppliers. We always strive to ensure that our collections provide top-quality yet affordable felt products for aluminum extrusion production. Our customers come from all over the world, and they highly praise the versatility, quality, durability, and overall value of our products and services.
If you want more information about our range of Kevlar and Nomex products, or if you need a quick quote, please feel free to send a message to toby@gdcalm.com. We will get back to you as soon as possible with your custom quote or an answer to your questions; we can’t wait to help!