Stephanie L. Kwolek, a chemist known for developing Kevlar fiber used in bullet-proof gear died at age 90 on June 18 at a hospice in Wilmington, Del. The cause of death is currently unknown.

Kwolek earned a degree in chemistry from Margaret Morrison Carnegie College of Carnegie Mellon University in 1946 and began her career at DuPont the same year. In 1964, her team began work on developing a lighter, more fuel-efficient alternative to metal reinforcements in tires to respond to an anticipated gasoline shortage. While working with poly-p-phenylene terephthalate and polybenzamide, she discovered that by reducing the temperature during the melt condensation polymerization process, the polymers formed a low viscosity solution.

After running tests with the new fiber, Kwolek was amazed to find that they were stronger than nylon and five times stronger than steel by weight. After more tests and making the fibers even stronger, modern Kevlar was introduced in 1971. Today, Kevlar has hundreds of modern applications, including bullet-proof vests, airplanes, ropes, sporting gear and more.

“Not in a thousand years did I think the discovery of this liquid solution would save thousands of lives,” Miss Kwolek told USA Today in 2003. “When I watch the war on TV, I take great pride in saying, ‘We at DuPont invented that.’ ”

Kwolek received many honors for her discovery, including:

  • Chemical Pioneer Award from the American Institute of Chemists (1980)
  • Award for Creative Invention from the American Chemical Society (1980)
  • Added to the National Inventors Hall of Fame (1995)
  • Lavoisier Medal for Technical Achievement from DuPont (1995); she is currently the only female employee to receive that honor.
  • National Medal of Technology (1996)
  • Perkin Medal from the American Chemical Society (1997)
  • Added to the National Women’s Hall of Fame (2003)