Stephanie Kwolek (born July 31, 1923) is a Polish-American chemist who discovered poly-paraphenylene terephtalamide, better known as Kevlar. Born in New Kensington, Pennsylvania, she joined DuPont as a chemist in 1946, specializing in low-temperature processes for the preparation of condensation polymers. In 1965 she discovered liquid-crystalline polymers, which she used to develop the Kevlar aramid fiber, which became the standard material for bulletproof vests, and led to the invention of several other everyday items which are either partially or totally made of Kevlar (e.g. heat-resistant helmets and gloves, canoes, sports equipment). July 31 is the 212th day (213th in leap years) of the year in the Gregorian Calendar, with 153 days remaining. ... 1923 (MCMXXIII) was a common year starting on Monday (link will take you to calendar). ... Kazimierz PuÅ‚aski monument in Washington. ... Chemist Julie Perkins of Lawrence Livermore National Laboratory pours from a Florence flask. ... Kevlar is the DuPont Companys brand name for material made out of synthetic fiber of poly-paraphenylene terephthalamide which is constructed of para-aramid fibers that the company claims is five times stronger than the same weight of steel, while being lightweight, flexible and comfortable. ... New Kensington is a city located in Westmoreland County, Pennsylvania, 18 miles (29 km) northeast of Pittsburgh, on the Allegheny river. ... Official language(s) None Capital Harrisburg Largest city Philadelphia Area  Ranked 33rd  - Total 46,055 sq. ... This article is about the DuPont company. ... This article is in need of attention. ... Bold text Schlieren texture of Liquid Crystal nematic phase Liquid crystals are substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. ... Kevlar is the DuPont Companys brand name for material made out of synthetic fiber of poly-paraphenylene terephthalamide which is constructed of para-aramid fibers that the company claims is five times stronger than the same weight of steel, while being lightweight, flexible and comfortable. ... Aramid fiber (1961) is a fire-resistant and strong synthetic fiber. ... Bullet resistant vest A bullet-resistant vest (body armor) - is an article of protective clothing that works as a form of armour to minimize injury from projectiles fired from handguns, shotguns and rifles . ...

She received her B.S. in chemistry from the Carnegie Institute of Technology (now Carnegie Mellon University) in 1946, originally hoping to continue to medical school. However, she lacked the money and instead took a job as a research chemist with DuPont.

DuPont was at the forefront of research into synthetic fibers, having discovered and brought to market nylon, Dacron polyester, Lycra spandex, and later Nomex aramid. Kwolek was part of a DuPont team working to find new synthetic fibers of commercial importance. (Her particular mandate was to find a synthetic fiber of use in tire manufacture. Ironically, it would be decades before the fiber she discovered was used this way). Nylon represents a family of synthetic polymers, a thermoplastic material, invented in 1935 by Wallace Carothers at DuPont. ... The term plastics covers a range of synthetic or semi-synthetic organic condensation or polymerization products that can be molded or extruded into objects or films or fibers. ... Lycra is INVISTAs trademark for a synthetic polyurethane-based elastane textile with elastic properties of the sort known generically as spandex. As with other spandex materials, Lycra is commonly used in athletic or active clothing, such as clothes for cycling, swimwear, leotards and dancewear, as well as in underclothes. ... Spandex or elastane is a synthetic fiber known for its exceptional elasticity (stretchability). ... NOMEX® is the brand name of a flame retardant meta-aramid material marketed and first discovered by DuPont in the 1970s. ...

Team members, including Kwolek, had a great deal of latitude in directing their own research. She in particular was working with a class of intractable para-oriented aromatic polyamides. These are composed of rodlike molecules, unlike the very flexible molecules in nylon and other synthetic fibers. The challenge was not only in synthesizing these molecules, but also in finding solvents that would allow DuPont to spin the molecules into thread.

Kevlar in solution did not resemble DuPont's successful molecules — it was cloudy, opalescent upon being stirred, and of low viscosity. The chemist in charge of running the 'spinning' machine at first refused even to test it. However, Kwolek persuaded him to try, and both were surprised to see that the kevlar solution was easy to spin into thread, and that once it had been spun, the threads were of tremendous strength.

Kwolek knew she had something important even before she ran rigorous tests on the fiber — the individual threads were hard to break by hand. When rigorously tested for tensile strength and other metrics, kevlar showed itself to be extraordinary. In the years since, a whole new field of polymer chemistry has been built upon Kwolek's discovery.

She holds 17 patents, was inducted into the National Inventors Hall of Fame in 1995, and received the National Medal of Technology in 1996.

Sources

• American Heritage of Invention and Technology, Winter 2003