In 1965, DuPont chemist Stephanie Kwolek invented Kevlar. By the 1970s, several Army agencies began work using layers of tough, puncture-resistant Kevlar 29, a synthetic ballistic fiber bonded with a synthetic polymer resin, to create a helmet capable of stopping most bullets, as well as shrapnel and shell fragments in a skull protecting device that weighed between 3.1 and 4.2 pounds.

- Smithsonianmag.com