Although the term is frequently used, it is essential to note that nothing is truly “bulletproof.” All materials have a limit to what they can withstand, and with enough power, velocity, or a specific type of projectile, all materials can eventually be penetrated. The more apt term would be “bullet-resistant.”
To date, Kevlar has been widely used in the creation of bullet-resistant vests, helmets, and other protective gear employed by the military and law enforcement. It had long been the “gold standard” for such material, but new composite fibers have entered the scene, offering lighter weight and/or higher strength.
Advances With Aramid Fiber
Kevlar has been among the most popular types of aramid fibers, known for their strength, heat resistance, and ability to absorb impacts and abrasions. Such fibers are also resistant to many organic solvents and chemicals, and have a low elongation at break, meaning that they stretch very little under tension.
However, the downside to Kevlar is that it has poor UV resistance, which causes it to degrade over time. It also had poor compressive strength.
Moreover, although Kevlar is lighter than steel, it is, pound for pound, far more effective at stopping bullets.
Scientists in China have recently developed a new composite material that could have the strength of Kevlar, but with a significantly thinner profile. The findings from their study were published in the journal Matter this month.
Jin Zhang from Peking University, in Beijing, China, and his colleagues created a new fiber that combined two unique materials. This included a heterocyclic aramid, a high-performance fiber similar to Kevlar, and treated long carbon nanotubes (tl-SWNTs). The result is a super-strong carbon tube that is stiff and lightweight, yet is thinner than human hair.
“Such optimization of hierarchical structures improves the interfacial interactions and enhances load transfer efficiency, inducing inhibited slippage and thus remarkable breakage of aramid chains under high-speed impacts,” the journal summary explained. “Fabrics woven from these fibers also exhibit superior anti-ballistic impact performance, shedding light on practical applications of these fibers. These findings provide fresh insights into the design of high-performance fibrous materials.”
The strength and toughness of the aramid fibers were the result of the orientation of the carbon nanotubes, which was also regulated by introducing a flexible monomer.
In plain English, the material is able to absorb more energy before failing, meaning it is more bullet-resistant than previous aramid materials, including Kevlar.
Better Body Armor
The Chinese researchers employed the new material in high-speed tests, including ballistic tests used to evaluate the performance of body armor. The improved material was able to absorb energy more than double the previous record.
“Our study not only presents an effective strategy for the fabrication of aramid fibers with ultra-high dynamic strength as well as the highest recorded dynamic toughness, but also provides fresh mechanism insights,” the team wrote in the paper.
This could result in the development of new protective equipment, including lighter and thinner ballistic vests, helmets, and other gear. That could be critical for success, as a helmet or body armor that isn’t comfortable won’t be worn, and certainly not for extended periods.
New U.S. Ballistic Standards
The development of new aramid materials followed the publication of the National Institute of Justice’s (NIJ) Ballistic Resistance of Body Armor, NIJ Standard 0101.07, in July. It specified minimum performance requirements and test methods for the ballistic resistance of body armor used by U.S. law enforcement, intended to protect the torso against handgun and rifle ammunition.
NIJ Standard 0101.07 is a revision of the previously published requirements from 2008.
Last March, the United States Department of Defense (DoD) awarded a $416 million federal contract to Hardwire LLC, of Pocomoke City, Maryland, to produce new protective gear for the U.S. Army.
It was part of the Army’s efforts to upgrade body armor systems for greater efficiency, customization, and comfort, and was expected to be 30% lighter than previous standard-issue armor.
With new developments in aramid chains, body armor will continue to evolve, becoming lighter and more effective at the same time.
