Stephanie Kwolek, an American chemist who in 1965 invented a super-strong fibre called Kevlar that revolutionised body armour and protected police officers and soldiers from bullets, has died at age 90.

Kwolek, who worked for the DuPont chemical company for four decades starting in 1946, died in Delaware after a short illness. The company confirmed her death.

The four-foot-11 Kwolek was working to find a fibre to strengthen radial tyres when she came across a thin, milky solution of polymers that showed real promise.

She told the News Journal newspaper in Wilmington, Delaware, in 2007 that it was not exactly a “eureka moment”. But it led to the development of Kevlar, now a critical part of bulletproof vests, helmets and other body armour components as well as a range of other applications like tyres, firefighter suits, boat hulls, fiber optic cables, fuel hoses, airplane and spacecraft parts and skis.

Kevlar is lightweight but extremely strong – five times tougher than steel.

“At least, I’m hoping I’m saving lives,” Kwolek told the newspaper.

She was careful to take credit for only the initial discovery of the technology that led to the development of Kevlar and credited the work of others involved in the efforts.

Kwolek was born on July 31, 1923, in New Kensington, Pennsylvania, graduated from Carnegie Institution of Technology with a chemistry degree and was hired by Dupont a year after the end of World War II.