Tuesday, January 1st, 2013

Polyurethane Stops Bullets, Could Work In Body Armor

A recent post on this blog described an English firm’s development of a technology combining polyester and aramid (Kevlar) fiber to provide ballistic protection such as explosion curtains and personal body armor. Other plastic materials also are vying for a share of the personal body armor/ballistic protection market, for example polyurethane (PUR).

Urethane, which can be a foam or solid, and very flexible or very rigid, already has a wide variety of applications and, but a photo I found of Edwin L. Thomas, materials scientist and Dean of the George R. Brown School of Engineering at RiceUniversity, holding a PUR disk with 9-mm bullets embedded is something new. The material had stopped the bullets, not by deflecting them, but by catching and sealing them inside the clear material. The PUR effectively had swallowed the slugs.

Polyurethane disk stops 9-mm bullets

Rice University scientists Edwin L. Thomas and Jae-Hwang Lee show a polyurethane disk that has stopped and captured three 9-mm bullets.

In collaboration with the Institute for Soldier Nanotechnologies at the Massachusetts Institute of Technology, a Rice University lab team led by Thomas and Jae-Hwang Lee began investigating the impact absorption characteristics of the PUR material. What intrigued them initially was seeing that, after the multiblock PUR copolymer disk swallowed the 9-mm bullets, it showed no macroscopic damage. It hadn’t failed, it hadn’t cracked, and you could still see through it. “This would be a great ballistic windshield material,” said Thomas.

What the scientists then wanted to learn was why it works the way it does. They decided that the investigative research, which was supported by the U.S. Army Research Office, would be done at the nanoscale level. And that meant that before work could even begin, the collaborating labs first had to

create nanoscale targets, microscale ammunition, and a method for firing the very tiny bullets. And so was born the laser-induced projectile impact test (LIPIT).

More detail on the research methodology and the results can be found here and in the video below. Detailed technical information is in a paper authored by the research team and published in the journal Nature Communications.

Following the nanoscale firing, the scientists were able to see what happened to the

parallel layers of the material as the bullet entered, which enabled them to understand what takes place to make the PUR copolymer, in Thomas’s words, “…such a great, high-performance, lightweight protection material.” Since that’s the holy grail of body armor material, we can expect to hear more about this — depending on security clearance.

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