In this NBC Learn video, part of a series on "Chance Discoveries" in chemistry, veteran NBC News war correspondent Richard Engel tells the story of lab work done in 1965 by DuPont chemist Stephanie Kwolek that unexpectedly produced Kevlar, a lightweight fiber five times stronger than steel. Kevlar fibers can be spun into anti-ballistic, shrapnel-resistant material for protective body armor worn by police forces, military troops and those in combat zones, including Engel himself.
Chance Discoveries: Kevlar
RICHARD ENGEL, reporting:
It's a revolutionary, life-saving material that helps protect soldiers, law enforcement officers, even journalists in war zones. Whenever I'm reporting from a war zone for NBC News, I wear this bulletproof jacket. It’s made of Kevlar. It can stop a bullet, or even shrapnel. It's five times stronger than steel, and believe it or not, this amazing material was discovered entirely by accident. The chance discovery happened in 1965 at DuPont headquarters in Wilmington, Delaware. With the boom in the automotive industry, manufacturers were looking for strong, heat-resistant materials to incorporate into tires.
DR. MICHAL MEYER (Editor-in-Chief Chemical Heritage): Tire companies started using steel wire to strengthen the tires. But they wanted something cheaper. So in that sense, here was an opening for the chemical companies to find something that tire makers could incorporate into their tires and make a better product.
ENGEL: DuPont wanted to capitalize on this opportunity and create lightweight, inexpensive synthetic fibers made from polymers, large molecules made up of individual units called monomers. To tackle the job, DuPont turned to Stephanie Kwolek, a veteran research chemist and inventor.
MEYER: Stephanie Kwolek was an excellent bench chemist, which means, she could be in the laboratory and work with the glassware and work with the chemicals and work with all of the instruments, and do an amazing job.
ENGEL: Kwolek's task was to create synthetic fibers from a tough, flame-resistant polymer made up of aromatic polyamides. To produce the fibers, she had to dissolve the polyamides in a solvent, then spin the resulting solution into fibers on a machine called a spinneret, a process similar to spinning cotton candy.
MEYER: The wonderful thing about polymers, you can produce much longer fibers, much longer threads in that sense. So what Stephanie Kwolek was trying to do was finding a way of dissolving this material that she was working with in a solvent, and then pulling it out, and stretching and twisting it into a fiber.
ENGEL: As Kwolek added more polyamides to the thickening solution, something unexpected happened: the mixture suddenly thinned out and formed a liquid crystalline solution, a state that was neither liquid nor solid.
MEYER: This would be as if you kept on adding flour, and it got thicker and thicker, until suddenly it gets thin again, which was completely unexpected. And this was because the polymer had turned into a liquid crystal.
ENGEL: The molecules of the polyamides had lined up side by side forming a solution that could be spun into fibers of incredible strength and stiffness.
MEYER: Normally with polymers, things are pointing in different directions. The fact that all these chains were aligned so closely together and all pointing in the same direction made them very, very strong.
ENGEL: DuPont began mass production of Kevlar in 1971. It replaced nylon in bulletproof vests in 1975. It's also used in military vehicles, gloves, and boots to protect soldiers from ballistic impact and heat. The International Association for Chiefs of Police estimates Kevlar has saved the lives of more than 3,000 law enforcement officers since 1987. The story of Kevlar and Stephanie Kwolek's skill and persistence in discovering it teaches us to take advantage of unexpected results.
MEYER: Use it as an opportunity to explore. Use it as an opportunity to listen to what the natural world is telling you. You might be surprised by what you find.
The silk of the humble spider has some pretty impressive properties. It’s one of the sturdiest materials found in nature, stronger than steel and tougher than Kevlar. It can be stretched several times its length before it breaks. For these reasons, replicating spider silk in the lab has been a bit of an obsession among materials scientists for decades.
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