Stephanie Kwolek, the genius behind Kevlar

What do bulletproof vests, oven gloves and fiber-optic cables have in common? What about frying pans, suspension bridges cables and skis? They are all strong, durable and resistant. The reason for this is that they are all frequently manufactured with Kevlar – a miracle material that is five times stronger than steel. Behind this incredible invention is a determined, curious and talented woman chemist, Stephanie Kwolek. This National Inventors Day (US), DiscovHER shares the story of a woman scientist whose invention has not only revolutionized the manufacturing of over 200 different products, but has also saved countless lives.

Stephanie Kwolek was born in Pennsylvania in 1923, the daughter of Polish immigrants. Her father was a keen naturalist who took young Stephanie exploring in the woods near their home, while her mother was a seamstress who passed her love of fabrics onto her daughter. Kwolek eventually became interested in chemistry, and studied at Margaret Morrison Carnegie College, what was then the women’s college of Carnegie Mellon University.

Not long after graduation, Kwolek looked for work in chemical companies, aiming to save up money to go to medical school. She was hired by the American chemical giant DuPont after a memorable interview with W. Hale Charch, who would go on to become her mentor. At the end of the interview, Charch told Kwolek he would let her know if she got the job in a few weeks’ time. Kwolek, however, proved to be a courageous negotiator: she told Charch she had another offer and needed a quicker response. Charch promptly dictated a job offer for Kwolek to his secretary right then and there.

Fascinated by the challenges of the polymer research she undertook at DuPont, Kwolek quickly dropped her plans to go medical school. In 1965, she was assigned to a project to look for the next generation of durable fiber to replace steel wires in tires – a looming gasoline shortage inspired DuPont to look for a lighter material that would ensure a better fuel economy. What Kwolek discovered turned out to be much bigger.

Nylon, a polymer, is traditionally spun at over 200°C. In a fateful experiment, Kwolek wanted to see what would happen if she manipulated these polymers at room temperature, and produced a watery, buttermilk-colored liquid that was unlike the clear, viscous fluids used to make nylon. She spent several days convincing a lab technician to spin the liquid in order to turn it into a fiber, in spite of his protests that it would block the delicate spinning machine. What happened next surprised both of them – the resulting fibers were extremely strong and stiff. So great was the potential of this discovery, that DuPont invested in a 15-year, $500-million-dollar development program!

Kwolek’s miracle material is now known as Kevlar. It is incredibly strong – five times stronger than steel – lightweight, and resistant to heat and corrosion. Its most well-known use is in making lightweight body armor and bulletproof vests, but it is also used in fighter jets, household objects like gloves and frying pans, cellphones, skis, boats… the list is long.

Kwolek’s work has earned her numerous accolades: she was inducted in the National Inventor’s Hall of Fame, she was won the National Medal of Technology, has three honorary degrees and is the only woman to have received DuPont’s extremely prestigious Lavoisier Medal for outstanding achievement.

Stephanie Kwolek died in 2014 after decades of hard work and 17 patents to her name. She continues to be an inspiration to women around the world.

Which do you think are the most important inventions made by women? Let us know @4womeninscience.

For Women in Science

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