A daughter of working-class Polish immigrants goes on to discover what Fortune magazine dubs “The miracle in search of a market.” Dr. Stephanie Kwolek passed away Friday, June 20th at the age of 90. But her legacy is far from silenced. In the 1950s and ‘60s Kwolek labored for years in DuPont’s laboratory, eventually discovering the unique chemical recipe that came to be known as Kevlar. The material was a boon to many, but perhaps none more so than the men and women law enforcement officers who don the ballistic vest to go to work every day. Since the 1970s when it was first used in public safety body armor, about ten years after Kwolek’s initial discovery, about 3,000 officers have been saved from bullet wounds through the use of equipment reinforced with Kevlar, a material far stronger than steel.
It was not long ago the necessity to replace natural rubber and find alternatives to glass paved the way for modern polymer science.
“Kevlar...is one of the most important polymer materials and fibers that belong to the class called aramids,” says Rigoberto Advincula, Ph.D., Associate Chair and Graduate Chair of the Department of Macromolecular Science and Engineering at Case Western Reserve University in Cleveland.
In the mid-1960s Kwolek struggled to convert a solid polymer into a liquid form. She expected to get a syrupy mixture—something that was viscous and clear—but instead she kept getting an opaque substance.Next she and her colleagues performed a process called “spinning,” in essence using a kind of centrifuge to separate liquid. This is how DuPont would make fibers like nylon.
David M. Manuta, Ph.D., FAIC and president of Manuta Chemical Consulting Inc.; explains spinning yields a kind of separation. The liquid is removed and what’s left behind are the polymers. “If you can get them to line up just so, in what we call an ‘orientation effect’, you can make them (the polymers) as strong as you want,” says Manuta.
After about 15 years of laboring with the substance Kwolek was able to get the polymers to line up in parallel, and when the liquid was cold spun it produced a fiber of unusual stiffness. Tests performed in 1965 found this new substance, in which all the polymers aligned, was five times as strong as steel, of equal weight, and resistant to fire.
Kwolek told USA Today in 2007 “I never in a thousand years expected that little liquid crystal to develop into what it did”.
As a young adult just stepping into the work world, Kwolek had little formal education compared with the majority of company-hired scientists today. Without adequate funds to cover tuition to medical school, her first choice, Kwolek began work at DuPont in 1946 armed with a bachelor’s degree from Pittsburgh’s Carnegie Institute of Technology.
The New York Times reported Kwolek was excited to go to work every day at the lab, where she worked for 15 years without a promotion before her breakthrough. She did not benefit financially from her discovery, but signed over patent royalties to DuPont.
“Marketing personnel at DuPont then embraced the challenge of finding applications for this unique formulation,” says Manuta.
Ellen Kullman, DuPont Chair and CEO called the ground-breaking scientist “a creative and determined chemist and a true pioneer for women in science.” In 1996 Kwolek became the company’s third scientist to win a National Medal of Technology of Science, just one of many awards. She was also an American Institute of Chemists (AIC) Chemical Pioneer awardee in 1980, and in 1996 was awarded the National Medal of Technology.
Science in public safety
Ballistic protection has come a long way since the early days of Kevlar. Today’s carriers are fitted with ceramic plates and multiple layers of Kevlar for bullet and stab resistance.
Chemically speaking, Dr. Advincula says while aramids are the most important classes of polymers used for ballistic protection, there are many other polymers that can be found in law enforcement, including polycarbonates, polypropylene, high density polyethylene (HDPE), nylon, polyurethane, etc. “Other uses include vest, helmets, textiles, visors, non-flammable vests or clothing, holsters, gun handles...even polymers that find their way in explosive (shaped charges). “Properties based on light weight, high mechanical strength relative to weight, non-flammability, and durability are always excellent properties for new functions and needs in law enforcement applications.”
Manuta is impressed with ongoing innovations in this field, such as specialized clothing developed for soldiers and personnel in Iraq and Afghanistan that circulate fluids, keep them cool and protected. Still, he says, it’s tough to make an apples to apples comparison.
In his eyes, Kwolek was “one-of-a-kind”...especially for her time. “People like me, we judge science fairs and we’re old enough to remember when almost no young women were going into science. As we mentor young people we want to remember there are a lot of talented young ladies. What a fantastic role model somebody like Dr. K. would be.”
In her later years, Kwolek was passionate about mentoring young women in the science fields.
On to new horizons
Imagine all the possibilities that still exist, based on her hard work and determination. Says Manuta, “If we were to look at her research notebooks there may be a dozen other innovative ideas that people haven’t yet picked up on. That’s part of the legacy, and an importance reason to honor people in their lifetimes.”
Coincidently, on the day Kwolek passed DuPont announced it had sold its one millionth vest made with new tech, Kevlar XP.
Despite all her accomplishments the brilliant Kwolek never forgot her roots—and perhaps it served her well.
“You don’t have to be a bright guy coming out of MIT to make important inventions, but just somebody who plugs away...and realizes ‘there’s something interesting going on here; let’s see what we can do with it’”, says Manuta.
Kevlar technology is at once strangely simple yet mystifyingly complex. At a whole four feet, 11 inches tall Kwolek was much the same—small in stature, but a masterful force in life.