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Stephanie Kwolek


American-Polish chemist Stephanie invented Kevlar®, the material used to make bulletproof vests and body armour.

A passion for science and textiles

Stephanie Kwolek with a molecular model

Stephanie was born in 1923 in New Kensington, Pennsylvania, the daughter of immigrants from Poland. Her father, who died when she was only 10 years old, was a keen naturalist and Stephanie attributed her love of science to him. They spent her early childhood exploring woods and fields together, collecting and identifying different leaves, wildflowers and seeds. Her mother was a seamstress and, from her, Stephanie developed a love of textiles.

Stephanie considered a career as a fashion designer but when her mother advised her that she was “too much of a perfectionist” to work in that industry, she instead went to study chemistry at Margaret Morrison Carnegie College, Pittsburgh. After graduating, Stephanie was eager to continue at university and study medicine. In order to fund this, she applied for the position of textile chemist at DuPont. She was interviewed by research director William Hale Charch who is credited with the development of water-proof cellophane. After the interview, when he told her that she would hear within a few weeks whether she had got the job, she stated that she had another job offer and pressed him to make his decision sooner. Charch then offered her the job on the spot, with Stephanie suspecting that her assertiveness was what influenced his decision. 

In her new role at DuPont Stephanie was able to combine her love of science and fabric and it wasn’t long before she became immersed in chemical research, abandoning any plans of becoming a medic.

“I was fortunate that I worked under men who were very much interested in making discoveries and inventions. Because they were so interested in what they were doing, they left me alone. I was able to experiment on my own, and I found this very stimulating. It appealed to the creative person in me.”*

The inventor of Kevlar

In 1965 DuPont began searching for a next-generation, high-performance, light-weight fibre which could replace the steel wire in vehicle tires and ensure better fuel economy.

Stephanie was tasked with synthesising long-chain aromatic polyamides, dissolving them in solvents and then spinning the resultant solutions into fibres. Whilst carrying out this research she produced a solution which was very peculiar: unlike the usual syrup-like polymer solutions, this one was thin and similar to buttermilk in appearance. This new solution was so odd that a co-worker initially refused to spin it for her, worried that it would clog his machines. After a change of heart, he agreed to test it and to his surprise, the solution spun easily into strong, stiff fibres – Kevlar.  

Stephanie Kwolek wearing Kevlar gloves

“It was unlike anything we had made before. I knew that I had made a discovery. I didn’t shout “Eureka!” but I was very excited, as was the whole laboratory. And management was excited, because we were looking for something new. Something different. And this was it.”*

Kevlar is a lightweight, heat-resistant fibre which is five times stronger than steel. Today, Kevlar can be found in hundreds of household and industrial appliances – from oven gloves and optic fibres, to tyres and walking boots. But it is perhaps best known as the fibre used to make stab and bullet proof vests and body armour. 

For her discovery, Stephanie was awarded DuPont’s Lavoisier Medal for outstanding technical achievement – the only woman to have received this award. She was also inducted into the National Inventors Hall of Fame. She retired in 1986 but continued to consult for DuPont and served on the committees of the National Research Council and the National Academy of Sciences.

Stephanie died on 18 June 2014, aged 90. Through the invention of Kevlar, she is credited with helping to save the lives of thousands of servicemen and women from around the world. And it was being able to use her research for the benefit of mankind which she found inspired her most.

“I don’t think there’s anything like saving someone’s life to bring you satisfaction and happiness.”*

Words by Isobel Marr
Images by DuPont and Michael Branscom / Courtesy of the Lemelson-MIT Program
Published July 2015

* Quotes taken from Stephanie Kwolek’s 2012 interview for Women in Chemistry, The Catalyst Series by Chemical Heritage Foundation.

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