Stephanie Louise Kwolek (July 31, 1923 – June 18, 2014) was an American chemist, whose career at the DuPont company spanned over forty years. She is best known for inventing the first of a family of synthetic fibers of exceptional strength and stiffness: poly-paraphenylene terephthalamide—better known as Kevlar. For her discovery, Kwolek was awarded the DuPont company’s Lavoisier Medal for outstanding technical achievement. As of February 2015, she was the only female employee to have received that honor. In 1995 she became the fourth woman to be added to the National Inventors Hall of Fame. Kwolek won numerous awards for her work in polymer chemistry, including the National Medal of Technology, the IRI Achievement Award and the Perkin Medal.
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, this high-strength material was first commercially used in the early 1970s as a replacement for steel in racing tires. Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite material components.