Engineers at the University of Wisconsin-Madison have created a material made of nanofibers that outperforms any technology currently used, such as steel plates or Kevlar, in protecting against high-velocity projectile impacts.According to its developers, the use of this material in the manufacture of spacecraft could serve as a shield against space junk that threatens vehicles in Earth orbit.“Our nanofiber mats have protective properties that far outperform other material systems, with a much lighter weight,” says Ramathasan Thevamaran, assistant professor of engineering physics at UW-Madison, who led the research, recently published in the journal ACS Nano.To create the material, Thevamaran and postdoctoral student Jizhe Cai mixed multiwall carbon nanotubes — cylinders of carbon just one atom thick in each layer — with Kevlar nanofibers.According to them, the resulting nanofiber mats are superior in dissipating the impact energy of small projectiles moving faster than the speed of sound.This advancement lays the groundwork for using carbon nanotubes in lightweight, high-performance armor materials, such as bulletproof vests to better protect the wearer, and shields around spacecraft to mitigate damage from debris in high speed.“Nanofiber materials are very useful for protective applications because nanoscale fibers have excellent strength, toughness and stiffness compared to macroscale fibers,” explained Thevamaran.“Carbon nanotube mats have shown the best energy absorption so far, and we wanted to see if we could improve their performance even further.”To do this, the team synthesized Kevlar nanofibers and incorporated a small amount of them into their carbon nanotube mats, creating hydrogen bonds between the fibers.These hydrogen bonds modified the interactions between the nanofibers and, together with the right amount of Kevlar nanofibers mixed with the carbon nanotubes, caused a considerable jump in the material's overall performance."Hydrogen bonding is a dynamic bond, which means it can break and repair itself continuously, allowing it to dissipate a high amount of energy through this dynamic process," Thevamaran said.“In addition, the hydrogen bonds provide more rigidity to this 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 almost 100% improvement in energy dissipation performance at certain supersonic impact speeds.”The researchers tested the new material using a laser-induced microprojectile impact testing system in Thevamaran's lab, using lasers to fire microbubbles at the material samples.“Our system was designed in such a way that we can actually take a single projectile under a microscope and shoot it at the target in a very controlled way, with a very controlled velocity that can range from 100 meters per second to over 1 kilometer per second.” , says Thevamaran."This allowed us to carry out experiments on a time scale where we could observe the material's response — as hydrogen bonding interactions take place."In addition to its impact resistance, another advantage of the new nanofiber material is that it is stable at very high and very low temperatures, making it useful for applications in a wide range of extreme environments.Have you watched the new videos on YouTube from Olhar Digital?Subscribe to the channel!