Nanotechnology engineers have developed a novel approach to modelling nanomaterials that employs their incredible strength for use in bulletproof protection. It is a discovery which offers soldiers and police officers body armour which weighs less, is more manoeuvrable, and with a better stopping force than current technologies, such as Kevlar.
The breakthrough centres around thin mats of material which combine two types of nanofibre to create a low-weight, flexible shield with excellent high-speed impact protection.
“Our nanofibre mats exhibit protective properties that far surpass other material systems at much lighter weight,” says the study’s lead-researcher Asst Prof. Ramathasan Thevamaran.
While carbon nanomaterials have always been known for their incredible strength (nanotubes are some of the strongest materials known to humanity), their tiny size has always limited their use in real world applications.
A fact that the study, now published in the American Chemical Society journal ACS Nano, acknowledges, stating, “Regardless of the superior intrinsic stiffness and strength of carbon nanotubes (CNTs), the weak nature of van der Waals interactions limits CNT mats from achieving greater performance.”
This weakness was overcome by reinforcing the carbon nanotube mats with Kevlar nanofibres which function as hydrogen bonds, causing a significant leap in the overall performance of the material.
“The hydrogen bond is a dynamic bond, which means it can continuously break and re-form again, allowing it to dissipate a high amount of energy through this dynamic process,” explains Thevamaran. “In addition, hydrogen bonds provide more stiffness to that interaction, which strengthens and stiffens the nanofiber mat. When we modified the interfacial interactions in our mats by adding Kevlar nanofibers, we were able to achieve nearly 100% improvement in energy dissipation performance at certain supersonic impact velocities.”
The results from this technique have produced a material described as, “Fundamentally, better than bulletproof.”
The new nanomaterial mats were devised and analysed at the University of Wisconsin-Madison’s specialised laboratory which contains a laser-induced microprojectile impact testing system. A testing device which uses lasers to fire micro-bullets into the material samples.
“Our system is designed such that we can actually pick a single bullet under a microscope and shoot it against the target in a very controlled way, with a very controlled velocity that can be varied from 100 meters per second all the way to over 1 kilometre per second,” says Thevamaran. “This allowed us to conduct experiments at a time scale where we could observe the material’s response — as the hydrogen bond interactions happen.”
As the nanomaterial journal AzoNano, explains, “Thevamaran and postdoctoral researcher Jizhe Cai blended multi-walled carbon nanotubes — carbon cylinders just one atom thick in each layer — with Kevlar nanofibers. The ensuing nanofiber mats are better at dispelling energy from the impact of miniature projectiles traveling faster than the speed of sound.”
Beyond bullet-proofing, the nanomaterials mats could be developed for use in other protective barriers, such as sports equipment, car bumpers, and protective screens in testing laboratories and firing ranges. The military could also use a version of the mats as improved deflective plates on tanks, aircraft, and other hardware.
Spacecraft and satellites can also be shielded as new nanofibre material is very stable at both extremely high and low temperatures. Beyond the atmosphere, objects are constantly barraged by micro-debris which orbits the planet at high speeds as well as impacts from cosmic dust travelling at speeds of up to 70 kilometres per second.
For now, though, the researchers have patents pending on ways to make life safer for police officers and soldiers with a high-performance body armour enhanced with nanomaterials.