Over the past half century, the primary fiber for use in soft body armor applications has been Aramid fiber (known commercially as Kevlar or Twaron). And though continued innovations and improvements have kept this fiber at the top of the heap in overall effectiveness, it is nearing its plateau. There is only so much that can be done with the (admittedly excellent) fiber, and a worthy successor has been chosen.
Some time ago, it turns out.
Originally developed in 1998 by Azko Nobel, M5 was first produced by Magellan, and subsequently by Dupont, which purchased the rights from Magellan in 2005. With a modulus of around 310 GPa and tenacity of around 5.8 GPa, it exceeds every current high-strength fiber (with the exception of carbon nanotube fibers) by a large margin.
It derives its great strength, in part, from its ability to form hydrogen bonds in 4 axes (by comparison, Aramid only forms biaxial hydrogen bonds). In addition, it is more flame resistant than Nomex, and exhibits almost no degradation when exposed to UV light. It also tolerates humidity well. Essentially, it shows none of the weaknesses inherent in current ballistic fibers, while being far stronger and tougher.
So why are we not seeing this fiber in commercial armor yet? Well, it is in part due to the exceptional characteristics. M5 requires “tempering,” which is a combination of heat treating and tensioning of the fibers as they come off the spinnerets. Unfortunately, equipment designed for Kevlar would be destroyed if it was used for processing M5, simply due to the incredible strength of the fiber. It is thought that much of the delay in bringing this fiber to market is due to the massive retrofitting required to process it into fabric.
One thing is for certain- the translucent blue M5 fiber will eventually replace the iconic golden yellow Aramid fiber as top dog in ballistic armor. Keep your eyes on M5, it will make quite a splash when it goes live.