Stephanie Kwolek Inventor of Kevlar Dead at 90

Stephanie Kwolek

Stephanie Kwolek, inventor of Kevlar®, died peacefully in Tallyville, Delaware, on Wednesday, June 18, 2014, at the age of 90. Kwolek was born on July 31, 1923 in New Kensington, a suburb of Pittsburgh, Pennsylvania and christened Stephanie Louise Kwolek. Her mother and father were Polish immigrants. Her father, John Kwolek, was a foundry worker but a naturalist by avocation. He spent many hours with Stephanie in the outdoors, teaching her a love of nature as they explored the many streams and woods around their house. Her mother, Nellie (Zajdel) Kwolek, instilled in her an interest in fashion and clothing materials.

Kwolek attributed her love of science and math to her father. Her mother’s influence caused her to spend many hours at home drawing different types of clothing in the hopes of one day being a fashion designer. She took up sewing and had a fine appreciation for materials and cloths. In high school she constantly struggled with a career path, and was continually conflicted about a satisfying career choice, a life in science or a pursuit of fashion, designing clothes.

Her higher education almost never occurred however, because her father passed away when she was ten. It was the early 1930s and her mother took up the torch of raising Stephanie and her brother. Nellie Kwolek was fortunate enough to secure employment at the Aluminum Company of America. The depression still had a strong grip on the country and many families were hit hard. Nellie Kwolek however, decided her children were to be college educated.

Kwolek’s love of science and math were well suited to her and she aspired to be a medical doctor. In 1946 Kwolek graduated from Carnegie-Mellon Univeristy with a degree in chemistry and began looking for a temporary position to earn enough money to enter medical school. After applying with several large commercial companies, she pressured the interviewer at DuPont into making a choice right away, as she had offers from two other companies.

She was hired at DuPont and began working in the Textile Lab at DuPont’s Buffalo, New York facility. Kwolek began her career with DuPont, a company famous for inventing many products through chemistry, such as Corian, Teflon and Kevlar to name a few. Once she began work at DuPont she found the work so exciting and challenging her plans to become a doctor fell away, and she immersed herself in the research of polymers. In 1950 she moved to Wilmington, Delaware and continued to work for DuPont there. She was absorbed by the work, never married, and stayed with DuPont until her retirement.

Kwolek, like many of her subordinates, began combining substances to make a polymer, melt it to a liquid and use a spineret to turn it into a fiber. After this process other scientists would test them for strength, weight, flexibility, and to see if they stretched or broke under various conditions. Many polymers died in solution and were cast aside. During this time she found two polymers that were not melting. She needed to find some type of solvent that would transform them into a liquid so they could be spun into a fiber. She found a solvent that melted one of the polymers into a liquid. This polymer was unlike any previous polymer she had worked with; most polymers in a liquid state are like molasses only more fluid. This solution was cloudy and runny, more like water. Kwolek’s work with low temperature polymers was the breakthrough in the invention of Kevlar. Kevlar inventor Stephanie Kwolek passed away at 90 in the same week the one millionth bullet-resistant vest was sold.


Kwolek had discovered a new fiber, named an aramid fiber, and a new substance, liquid crystalline solutions. Kwolek herself was always amazed at what had happened and said her discovery was a complete case of serendipity. Kwolek retired from DuPont in 1986. She received numerous scientific awards over the years and her discovery and the subsequent use of material made of Kevlar as a bullet-resistent vest has saved thousands of lives.

Some of the awards are the Kilby Award, the National Medal of Technology and the 1999 Lemelson-MIT Lifetime Achievement Award. According to her long time friend, Rita Vasta, Kwolek was a great mentor to her when they both worked at DuPont. Vasta stated Kwolek was also a consultant to DuPont after her retirement and a mentor to other women. Stephanie Louise Kwolek, inventor of Kevlar, was 90 when she passed away.

By Andy Towle

Delaware Online
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