WILMINGTON, Del. (June 23, 2014) — Chemist Stephanie Kwolek, the inventor of aramid fiber, died June 18, following a brief illness. She was 90.
A low-key industrial chemist at DuPont Co. who achieved international fame, Ms. Kwolek discovered the material — tradenamed Kevlar by DuPont — in the mid-1960s. The fiber has been used in body armor that has saved countless lives of soldiers, police and other safety personnel, and was adapted for numerous other uses, including as a reinforcing material in tires.
DuPont commercialized Kevlar in 1971, with the material most famously going into bulletproof vests but also used to make super-strong rope, protective gloves for meat packers, fiber-optic cables and as a reinforcement for composites used in a host of products, including tires, conveyor belting and other rubber products.
Ms. Kwolek was inducted into the Plastics Hall of Fame in 1997 — she is still the only woman in the hall today. That same year, she received the prestigious Perkin Medal from the Society of Chemical Industry's American Section. Ms. Kwolek entered the National Inventors Hall of Fame in 1995. She also is a member of the Engineering and Science Hall of Fame. In 1996, she received the National Medal of Technology in a White House ceremony.
Kevlar aramid fibers are, by weight, five times stronger than steel.
The International Association of Chiefs of Police reports that more than 3,100 law enforcement officers have been inducted into the IADP/DuPont Kevlar Survivors' Club. The organization documents when a bulletproof vest saves a life. Many of these survivors met Ms. Kwolek and poured out their emotions and thanks. She signed many of their Kevlar vests.
She also starred in DuPont advertisements.
But Ms. Kwolek did her work quietly — in the laboratory. She joined DuPont in 1946, but the company already was a well-known fiber innovator thanks to nylon, Dacron polyester and Lycra spandex when Ms. Kwolek began her work leading to Kevlar.
At first, the researchers wanted to develop a lightweight fiber for tires that would boost gas mileage in cars, she recalled in a profile for Plastics News, a sister publication of Tire Business, when she entered the Plastics Hall of Fame.
Ms. Kwolek was trying to find a good solution for spinning the fibers. She hit on dissolving poly(butylene) adipate (PBA) in amide/salt solvents. She described the details of invention in a 1993 speech: “The solution was unusually (low viscosity), turbid, stir-opalescent and buttermilk in appearance. Conventional polymer solutions are usually clear or translucent and have the viscosity of molasses, more or less.
“The solution that I prepared looked like a dispersion but was totally filterable through a fine pore filter. This was a liquid crystalline solution, but I did now know it at the time.”
The researchers were surprised when the fibers appeared to be super-strong.
“Lest a mistake had been made, I did not report these unexpected results until I had the fibers retested several times,” she said.
Ms. Kwolek learned that the fibers could be made even stronger by heat-treating them. The polymer molecules, shaped like rods or matchsticks, are highly oriented, which gives Kevlar its extraordinary strength.
Ms. Kwolek gave frequent talks to students, encouraging them to get into science. Tire makers eventually adopted cheaper steel-belted radials, deciding against Ms. Kwolek's invention on a broad scale.
Still, Kevlar went on to greater fame: Stopping bullets and saving lives.
Ms. Kwolek was described as “exceptional” by Jay Gardiner, president of the Plastics Academy, which administers the Plastics Hall of Fame. Kevlar is an example of a super-tough material that shows the public that plastics are far more than “cheap” and disposable, he said.
DuPont Chairman and CEO Ellen Kullman said in a statement: “We are all saddened at the passing of DuPont scientist Stephanie Kwolek, a creative and determined chemist and a true pioneer for women in science.…
“She leaves a wonderful legacy of thousands of lives saved and countless injuries prevented by products made possible by her discovery.”
Ms. Kwolek spoke about her life and work in this 2013 video from the Museum of Science in Boston.
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This report appeared in Plastics News, a Detroit-based sister publication of Tire Business. Mr. Bregar can be reached at [email protected].
