The inventor of Kevlar has died at 90

Stephanie L. Kwolek, the DuPont chemist primarily credited with the invention of Kevlar, died today at the age of 90. Nearly fifty years ago, in 1965, she created a cloudy liquid polymer solution that seemed to be a disappointment at first. When spun into a fiber, however, the resulting material was incredibly strong and lightweight -- pound for pound, it was five times stronger than steel. And it was fire resistant, to boot. Her discovery ultimately led to Kevlar fabric, though DuPont spent 15 ...