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Stephanie Kwolek

The DuPont chemist who gave us Kevlar

Created date

August 21st, 2015
Stephanie Kwolek
Stephanie Kwolek

Stephanie Kwolek’s name isn’t exactly front-and-center in the records of American invention, but it should be. Few technological innovators throughout history could lay claim to saving so many lives.

Born in 1923 to Polish immigrants in New Kensington, Pa., Kwolek was a naturally inquisitive child. Science and the wonders of the natural world fascinated her—a passion that she inherited from her father, a semi-professional naturalist who died when she was just ten years old.

Despite having lost him at such a young age, Kwolek’s interest in science deepened in the years following his death. 

By the time she entered college in 1942, she had already made plans to become a doctor.

She majored in chemistry at Carnegie Mellon University, and upon earning her bachelor of science, she began looking for employment to help save money for medical school. After her graduation in 1946, she received a job offer as a chemist at DuPont’s Buffalo, N.Y., lab.

Finding her calling at DuPont

At first, Kwolek considered the position temporary, intending to go on to medical school as soon as she was financially able. But as it turned out, she actually loved working as a chemist; the process of experimenting with chemical substances and exploring their possible applications was exciting to her.

Kwolek realized that chemistry wasn’t a mere stepping stone, it was her calling. So, in 1950, she abandoned any thoughts of becoming a doctor and transferred to DuPont’s facility in Wilmington, Del.

Here she would make one of the most important discoveries in the history of her field. 

It all started in 1965, when DuPont’s leadership focused the company’s research efforts on addressing an impending gas shortage. Kwolek’s assignment was to develop a strong yet lightweight fiber for the manufacture of more fuel-efficient tires. 

Instead, she found something bigger than she could have imagined.

Part of Kwolek’s work involved improving the process by which DuPont could heat and spin liquid crystalline polymers into a fibrous material like nylon. Her other objective was to create a superior polymer that the company could use to do this.

Persistence pays off

As she tinkered with various combinations of polymers, she noticed certain properties she hadn’t seen before.

Typically, the liquid solutions she saw were clear with a thick, syrupy viscosity. Suddenly, she had one that was cloudy and thinner. 

Chemists would normally have disposed of the strange substance; however, Kwolek persuaded a technician to spin it into a fiber for testing. The result was astonishing.

Immediately, she realized that the strength of the new fiber far exceeded that of nylon. In fact, because of its unique molecular composition, it was five times stronger than steel by weight. 

When Kwolek showed it to her supervisor, the magnitude of her discovery was instantly apparent. Further research into the product’s potential uses continued into the 1970s, after which DuPont introduced the world to Kevlar.

The National Institute of Justice was among the first organizations to embrace this remarkable technology. Following a rigorous evaluation, the Institute concluded that Kevlar was an effective, lightweight body armor that law enforcement officers could comfortably wear on a daily basis.

In 1975, wearable Kevlar vests hit the market under companies like American Body Armor and Second Chance Body Armor. By the late 1980s, an estimated 50% of all patrol officers wore Kevlar with their uniforms.

The gold standard

The vests available today are capable of stopping projectiles ranging from 9 mm, .357, and .45 caliber pistol rounds to 7.62 mm and .30-06 cartridges, the latter two used in high-powered rifles. Since its introduction almost 50 years ago, Kevlar has saved thousands of police and military lives and remains the gold standard in bullet-resistant material.

As for the woman responsible for its discovery, Kwolek did not profit from her innovation. Indeed, she signed the patent over to DuPont, where she stayed on as a chemist until her retirement in 1986.

To Kwolek, the money didn’t matter. For her, it was reward enough to save lives, a position she maintained until her death in 2014.