What Are Carbon-Based Fibers?
The most basic building block of FR fabrics is fiber, and one of the most basic building blocks of life is carbon. Carbon is an inert material that is very light and has excellent energy absorption qualities. Carbon fiber’s high strength and low weight makes it ideal for applications where the finished product needs to be as light and as strong as possible (1). Therefore, it only makes sense that carbon fiber would eventually be incorporated into FR fabrics.
As it turns out, carbon-based fibers are ideal for secondary protective apparel. In 2003, tests at the University of Texas showed that carbon threads were 17 times stronger than spider silk, suggesting some potential applications that rely on high fiber strength – namely protective clothing (2). Secondary protective clothing is designed for continuous wear in situations where intermittent exposure to flame or radiant heat is possible. Primary protective clothing mostly refers to firefighter turnout gear for use in situations where significant exposure to radiant heat and flame is likely to occur.
How Do Carbon-Based FR Fabrics Work?
The goal with carbon-based fiber is to provide better protection at a lighter weight. Companies like TECGEN®, Spentex® and CarbonX® have created fibers where carbon is “wrapped” in other FR fibers. The use of carbon saves approximately one ounce in fabric weight while maintaining protective parity, which translates into more protection per unit of weight. In fact, carbon-based fibers stand up to flame, arc flash and other extreme fire conditions workers face better than traditional flame resistant products because it has a higher density than other fibers. See the image above for an actual microscopic photo of TECGEN® fiber.
Additionally, since carbon is inherently flame resistant, FR garments made with carbon will not be degraded with laundering. This means the FR qualities of the garments will not wash out or wear away over time.
Limitations of Carbon
Carbon-based fabrics face a few textile challenges:
Manufacturing/Cost – Significant amounts of energy are used to achieve the high temperatures required in the production process used to create carbon fiber. This contributes to a relatively high cost of carbon when compared to other materials.
Color – Carbon-based fabrics can be more difficult and costly to dye. Since the carbon is “wrapped” in other FR fibers, there are limitations to the color carbon fibers can achieve through the dyeing process.
Garment Cutting – The characteristics of carbon make garment cutting more difficult than with other fabrics. This results in more mistakes, more error and more waste during the manufacturing process than with other fabrics used in garment production.
Traditional Sewing Techniques – Equipment that is used to sew garments is not made for carbon-based fibers. Carbon has the tendency to wear through equipment much faster, dulling the needle and contributing to other difficulties in the sewing process.
In the end, this emerging technology allows FR fabrics to be developed that offer advanced heat and flame protection capabilities. It will be interesting to see where this technology goes and how it contributes to advancements in FR apparel.
References for this post were accessed Dec 2013: