Bulletproof fabric is both lightweight and durable.
Jin Zhang Group, Peking University
The new material is so strong that just a 1.8mm thick sheet can stop a bullet, making it much stronger than Kevlar and possibly the strongest fabric ever created.
Bulletproof vests distribute the energy of a projectile through a network of interconnected fibers. In the case of Kevlar, these fibers are made from aramids, a group of chemicals with polymer chains known for their extreme strength. However, under extreme stress, these polymer chains can slip, limiting the protection they provide.
Over the past six years, Jin Zhang at Peking University in China, and his colleagues were trying to develop even stronger materials than Kevlar or Dyneema, which are another type of polyethylene fiber and are often called the world's strongest fabric.
“Ultra-high dynamic strength and toughness are critical for fiber materials in the field of impact protection,” says Zhang. “These include bulletproof armor, vehicles and aircraft.”
Now his team has developed a method of combining carbon nanotubes with aramid polymer chains to prevent the molecules from slipping. “Our new fiber is significantly superior to all known macroscopic high-performance polymer fibers,” says Zhang. “Our fabric is completely superior to Kevlar.”
The new material is “a composite of carbon nanotubes and heterocyclic aramid,” Zhang says, but he hopes to come up with a cooler name like Kevlar “later.”
Because this material is stronger than Kevlar, the same bulletproof effect can be achieved using much less material. One layer of fabric is about 0.6 millimeters thick and can reduce the speed of a bullet traveling at 300 meters per second to 220 m/s, Zhang says. “Based on energy absorption calculations, approximately three layers of fabric are sufficient to stop a bullet,” with a total thickness of 1.8mm. By comparison, Kevlar would have to be at least 4mm thick to stop the same bullet.
Julie Cairney from the University of Sydney (Australia) believe that the combination of aramid fibers and oriented carbon nanotubes is innovative.
“This approach could potentially be used to produce other new composites,” says Cairney. She also says the manufacturing strategy is compatible with existing industrial processes, making it promising for scalable production and real-world implementation.
“For personal and military protection, these materials can be used to make lighter, more effective body armor and body armor, increasing safety without sacrificing mobility,” she says.
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