Stephanie L. Kwolek, a DuPont chemist who invented the technology behind Kevlar, a virtually bulletproof fiber that has saved thousands of lives, died on Wednesday in Wilmington, Del. She was 90.

The chief executive of DuPont, Ellen Kullman, announced the death, calling Ms. Kwolek, who spent 15 years in the laboratory without a promotion before her breakthrough, “a true pioneer for women in science.”

Kevlar is probably best known for use in body armor, particularly bulletproof vests. A DuPont spokeswoman estimated that since the 1970s, 3,000 police officers have been saved from bullet wounds through the use of equipment reinforced with Kevlar, which is far stronger and lighter than steel.

The product has found its way into all corners of the modern world. It has been used in car tires, boots for firefighters, hockey sticks, cut-resistant gloves, fiber-optic cables, fire-resistant mattresses, armored limousines and even canoes. It is used in building materials, making them bomb-resistant. Safe rooms have been built with Kevlar to protect a building’s occupants during hurricanes. Kevlar has been used to reinforce overtaxed bridges.