Kevlar and Twaron are known for their tough materials, but there is a trade-off between strength, heat resistance and weight, according tomedia reports. Now, researchers at Harvard University have created a new version of the nanofiber material that has the same strength but is more insulated.
Kevlar and Twaron’s protective properties come from their molecular structures, which change their effectiveness. For mechanical strikes, such as bulletproof vests, the material presents a highly ordered structure that allows it to redistribute power. Insulation materials have more porous structures that minimize the heat passing through.
Often, due to the basic properties of the material, it is difficult to design equipment designed to protect the limb from extreme temperatures and the deadly projectiles that accompany an explosion. Materials strong enough to withstand ballistic threats cannot withstand extreme temperatures, and vice versa. As a result, most of today’s protective equipment is made up of multiple layers of different materials, resulting in bulky and heavy equipment that, if worn on the arms and legs, severely limits the ability of soldiers to move. Now researchers are starting to combine two types of materials into one.
“Our goal is to design a versatile material that protects people working in extreme environments, such as astronauts, firefighters, or soldiers, from the many different threats they face,” said Grant Gonzalez, the study’s lead author. To do this, the researchers need to combine these two types of molecular structures — highly organized and porous — into a single material. It is made from a process called soaked rotary jet spinning (iRJS). Basically, a device rotates and forces a liquid polymer solution to flow through a small hole, forming a long polymer chain. It hit a liquid bath nailed to the wall of the centrifuge and solidified. These solid lines then gather around the base.
The researchers were able to adjust the viscosity of the starting polymer liquid so that the final thread had the desired properties. Finally, they were able to produce long, neatly arranged pieces of nanofibers with many pores between them. Next, they have to test whether nanofiber slivers really protect both ballistics and heat. In tests that fired BB-like projectiles at stacked sheets, the team found that the new material was as durable as a regular Twaron braid.
In thermal testing, the researchers found that the new material was about 20 times more insulated than commercial Twaron and Kevlar. Using the current setup, the team was able to spin out a sheet measuring about 10 x 30 cm (3.9 x 11.8 inches) in about 10 minutes, but this could be improved if production is scaled up.
“While there is room for improvement, we have pushed the boundaries beyond the possibility and are beginning to move towards this multi-functional material stake,” Gonzalez said.
The study was published in the journal Matter.