Births on July 31

Stephanie Kwolek, American chemist and engineer, invented Kevlar (d. 2014)

Stephanie Louise Kwolek (; July 31, 1923 – June 18, 2014) was a Polish-American chemist who is known for inventing Kevlar. Her career at the DuPont company spanned more than 40 years. She discovered the first of a family of synthetic fibers of exceptional strength and stiffness: poly-paraphenylene terephthalamide.For her discovery, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement. As of August 2019, 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.