Stephanie Kwolek, Inventor of Kevlar®
Fibers Stronger than Steel used in Bulletproof Vests
Sep 18, 2009
As a scientist at DuPont, Kwolek stumbled upon the right mixture and created a fiber capable of stopping a bullet.
Born in 1923 in New Kensington, Pennsylvania, Stephanie Kwolek didn't set out to be an inventor. Influenced by both parents, Kwolek developed an interest in math and science thanks to her father who encouraged her to appreciate nature as well. Her mother inspired in her a love for fashion.
Scientist at DuPont
As a child, Kwolek wanted to be a fashion designer. She spent a lot of time drawing clothes and sewing. But in school, Kwolek developed an interest in science and math. Her teachers supported her interest and discussed careers in science and chemistry.
It was in high school that Kwolek decided to go into the field of medicine. Kwolek attended a women's college (now Carnegie Mellon University) where she majored in chemistry. But, in order to attend medical school, Kwolek needed to earn some money.
She interviewed with several companies, including DuPont. The interviewer told Kwolek it would be a few weeks before she would be notified of her possible employment. Kwolek decided to be bold and said, "I wonder if you could tell me sooner, because I have some companies requesting that I give them an answer whether I will accept their offers or not." Her boldness paid off as she was hired as a scientist at DuPont on the spot.
Kwolek loved her job at the Textile Lab at DuPont so much that she completely forgot about medical school.
Discovering Kevlar
Kwolek's work at DuPont consisted mainly of working with polymers with possible commercial uses. Using a solvent to dissolve a polymer she one day came upon a mixture which didn't react as other mixtures had reacted. The solution separated into two layers, one which was yellow and clear and one which was iridescent and cloudy. Further, the solution acted more like water instead of having the trait of thickness that previous solutions had exhibited.
The solution was then placed into a spinneret which turned the solution into fibers. These fibers turned out to be resilient, strong and lightweight. The discovery of aramid fibers and liquid crystalline solutions was credited to Kwolek.
It took ten years before Kevlar to be marketed and used for bullet-proof vests. Commercial uses for the fiber were discussed, patents were issued and the product had to be fully developed before the substance was available.
A vest made from Kevlar uses seven layers but only weighs 2.5 pounds. But it can stop a .38-caliber bullet from ten feet away. Aramid polymers are used for boat hulls, fiber-optic cables, helmets, parts of airplanes and a host of other products.
Kwolek's name is on a total of 16 patents, seven of which she is the sole patent holder. She has presented her work at conferences and authored or co-authored 28 scientific publications. She also won a publication award from the American Chemical Society in 1959.
Although Kwolek is retired, she continues to perform as a consultant to the DuPont Company and also serves on the National Research Council and the National Academy of Sciences. She occasionally takes time from her hobbies of sewing and gardening to give lectures.
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