Stephanie Kwolek

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Stephanie Kwolek
Stephanie Kwolek at Spinning Elements by Harry Kalish.TIF
Stephanie Louise Kwolek

(1923-07-31)July 31, 1923
DiedJune 18, 2014(2014-06-18) (aged 90)
ResidenceWilmington, Delaware
Alma materCarnegie Mellon University
Known forKevlar
AwardsDuPont company's Lavoisier Medal (1995)
National Medal of Technology
Perkin Medal (1997)
Howard N. Potts Medal
Scientific career
FieldsOrganic chemistry

Stephanie Louise Kwolek (July 31, 1923 – June 18, 2014) was an American chemist, whose career at the DuPont company spanned over forty years.[1] She is best known for inventing the first of a family of synthetic fibers of exceptional strength and stiffness: poly-paraphenylene terephthalamide—better known as Kevlar.[1][2] For her discovery, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement. As of February 2015, she was the only female employee to have received that honor.[3] In 1995 she became the fourth woman to be added to the National Inventors Hall of Fame.[4] Kwolek won numerous awards for her work in polymer chemistry, including the National Medal of Technology, the IRI Achievement Award and the Perkin Medal.[5]

Early life and education

External video
Stephanie Kwolek Women in Chemistry from video.png
Stephanie Kwolek, "I don't think there's anything like saving someone's life to bring you satisfaction and happiness", "Women in Chemistry", Chemical Heritage Foundation[1]

Kwolek was born to Polish immigrant parents in the Pittsburgh suburb of New Kensington, Pennsylvania, in 1923.[6] Her father, John Kwolek[6] (Polish: Jan Chwałek), died when she was ten years old.[7] He was a naturalist by avocation, and Kwolek spent hours with him, as a child, exploring the natural world.[1] She attributed her interest in science to him and an interest in fashion to her mother, Nellie (Zajdel) Kwolek.[6][7]

In 1946, Kwolek earned a Bachelor of Science degree with a major in chemistry from Margaret Morrison Carnegie College of Carnegie Mellon University. She had planned to become a doctor and hoped she could earn enough money from a temporary job in a chemistry-related field to attend medical school.[7]

DuPont career

In 1946, Hale Charch, a future mentor to Kwolek, offered her a position at DuPont's Buffalo, New York, facility.[8] Charch had initially told Kwolek that he would contact her within two weeks, but after Kwolek said she had to answer another job offer and insisted on a faster reply, Charch immediately offered her the position.[7] She reportedly got her job because of the amount of men that were overseas at the time for World War II. She only kept her job after the war because of her extensive research on polymers.[9] While Kwolek initially only intended to work for DuPont temporarily, she found the work interesting and decided to stay rather than pursuing a medical career, moving to Wilmington, Delaware, in 1950 to continue to work for DuPont.[8] After about nine years with the company, she created Kevlar.[10] In 1959, she won the first of many awards, a publication award from the American Chemical Society (ACS).[5][11] The paper, The Nylon Rope Trick, demonstrated a way of producing nylon in a beaker at room temperature. It is still the basis of a common classroom experiment.[12]


While working for DuPont, Kwolek invented Kevlar.[7] In 1964, in anticipation of a gasoline shortage, her group began searching for a lightweight yet strong fiber to be used in tires.[7] The polymers she had been working with at the time, poly-p-phenylene terephthalate and polybenzamide,[13] formed liquid crystal while in solution that at the time had to be melt-spun at over 200 °C (392 °F), which produced weaker and less-stiff fibers. A unique technique in her new projects and the melt-condensation polymerization process was to reduce those temperatures to between 0–40 °C (32–104 °F).[7]

As she later explained 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 not know it at the time.”[14]

This sort of cloudy solution usually was thrown away. However, Kwolek persuaded technician Charles Smullen, who ran the spinneret, to test her solution. She was amazed to find that the new fiber would not break when nylon typically would. Not only was it stronger than nylon, Kevlar was five times stronger than steel by weight. Both her supervisor and the laboratory director understood the significance of her discovery, and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar was introduced.[7] 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.

Applications of Kevlar

Kwolek was not very involved in developing practical applications of Kevlar.[15] Once senior DuPont managers were informed of the discovery, they immediately assigned a whole group to work on different aspects," she said. She also did not profit from DuPont's products, as she signed over the Kevlar patent to the company.[16]

Kevlar is used as a material in more than 200 applications, including tennis rackets, skis, boats, airplanes, ropes, cables, tires, and bullet-proof vests.[1] It has been used for car tires, fire fighter boots, hockey sticks, cut-resistant gloves, and even armored cars. It has also been used for protective building materials like bomb proof materials, hurricane safe rooms, and overtaxed bridge reinforcements.[17] During the week of Kwolek's death, the one millionth bullet-resistant vest made with Kevlar was sold.[18] Kevlar is also used to build cellular telephones; Motorola's Droid RAZR has a Kevlar unibody.[19]

Awards and honors

For her discovery of Kevlar, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement in 1995, as a "Persistent experimentalist and role model whose discovery of liquid crystalline polyamides led to Kevlar aramid fibers."[20][21] At the time of her death in 2014, she was still the only female employee to receive that honor.[3] Her discovery generated several billion dollars of revenue for DuPont, being her employer at the time, but she never benefited directly from it financially.[17]

In 1980, Kwolek received the Chemical Pioneer Award from the American Institute of Chemists, and an Award for Creative Invention from the American Chemical Society.[5] In 1995,[8][22] Kwolek became the fourth woman to be added to the National Inventors Hall of Fame.[4] In 1996, she received the National Medal of Technology and the IRI Achievement Award. In 1997, she received the Perkin Medal from the American Chemical Society.[23] In 2003, she was added to the National Women's Hall of Fame.[6]

She has been awarded honorary degrees by Carnegie Mellon University (2001),[24] Worcester Polytechnic Institute (1981)[5] and Clarkson University (1997).[25]

Royal Society of Chemistry - Stephanie L Kwolek Award (2014)

The Royal Society of Chemistry grants a biennial 'Stephanie L Kwolek Award', "to recognise exceptional contributions to the area of materials chemistry from a scientist working outside the UK".[26]

Kwolek is featured as one of the Royal Society of Chemistry 175 Faces of Chemistry.[27]


In 1986, Kwolek retired as a research associate for DuPont. Toward the end of her life, she consulted for DuPont, and served on both the National Research Council and the National Academy of Sciences.[8] During her 40 years as a research scientist, she filed and received either 17[15] or 28 patents.[22]

After she retired she became heavily involved in trying to introduce young children, specifically girls, to scientific fields.[28] She often tutored students in chemistry.[17] She has also invented and wrote about numerous classroom demonstrations that are still used in schools today, such as the Nylon Rope Trick.[28]

Kwolek died at the age of 90 on June 18, 2014.[29]


  1. ^ a b c d e "Women in Chemistry – Stephanie Kwolek". Chemical Heritage Foundation. Retrieved June 13, 2013.
  2. ^ Wholly Aromatic Carbocyclic Polycarbonamide Fiber Original Kevlar patent awarded in 1974 to Stephanie Kwolek
  3. ^ a b "Kevlar inventor Stephanie Kwolek dies". BBC News. Retrieved June 21, 2014.
  4. ^ a b "Citation conferring an Honorary Doctor of Science degree on Stephanie Louise Kwolek". University of Delaware. UDaily. May 31, 2008. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  5. ^ a b c d "Interview with Stephanie L Kwolek, March 21, 1998". Center for Oral History, Chemical Heritage Foundation. Retrieved 22 June 2014. External link in |publisher= (help)
  6. ^ a b c d "Stephanie Kwolek". Soylent Communications. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  7. ^ a b c d e f g h "Inventing Modern America: Insight — Stephanie Kwolek:". Lemelson-MIT program. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  8. ^ a b c d "Invent Now". National Inventors Hall of Fame. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  9. ^ "Stephanie Kwolek, Chemist Who Created Kevlar, Dies At 90." NPR. NPR. Web. 8 Nov. 2015.
  10. ^ "Stephanie Kwolek." Famous Scientists. Web. 8 Nov. 2015.
  11. ^ Rossiter, Margaret W. (1998). Women Scientists in America. Baltimore, Maryland: Johns Hopkins University Press. p. 267. ISBN 0-8018-5711-2. Retrieved May 24, 2009.
  12. ^ "Stephanie Kwolek obituary". The Guardian. 28 June 2014.
  13. ^ "Stephanie Louise Kwolek Biography". Bookrags. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  14. ^ Bill Bregar. "Obituary Kevlar inventor Stephanie Kwolek". Retrieved June 21, 2014.
  15. ^ a b Quinn, Jim. "I was able to be Creative and work as hard as I wanted". American Heritage Publishing. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  16. ^ Jeremy Pearce. "Stephanie L. Kwolek, Inventor of Kevlar, Is Dead at 90". New York Times. Retrieved June 21, 2014.
  17. ^ a b c Pearce, Jeremy. "Stephanie Kwolek, Inventor of Kevlar, Is Dead at 90: [Obituary (Obit); Biography]." ProQuest. New York Times, 1 June 2014. Web. 8 Nov. 2015.
  18. ^ Newcomb, Alyssa (June 20, 2014). "Kevlar Inventor Stephanie Kwolek Dead at 90". Good Morning America.
  19. ^ "Motorola Droid RAZR: Thinnest of All. Kevlar. Splashproof. Yes". Gizmodo. 18 October 2011. Retrieved 22 June 2014.
  20. ^ "Welcome to the Global Collaboratory: Lavoisier Medal for Technical Achievement" (PDF). DuPont. Retrieved 22 June 2014.
  22. ^ a b "The History of Kevlar — Stephanie Kwolek:". The New York Times Company. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  23. ^ "JCE Online: Biographical Snapshots: Snapshot". American Chemical Society. Journal of Chemical Education. Archived from the original on May 24, 2009. Retrieved May 24, 2009.
  24. ^ "Obituary: Carnegie Mellon Alumna and Hall of Fame Inventor Stephanie Kwolek Dies at 90". Carnegie Mellon News. Carnegie Mellon University. June 20, 2014. Retrieved 7 October 2014.
  25. ^ "Honorary Degrees". Clarkson University. Retrieved 7 October 2014.
  26. ^ "RSC Stephanie L Kwolek Award". Royal Society of Chemistry. Retrieved 14 November 2014.
  27. ^ "Stephanie Kwolek | 175 Faces of Chemistry". Retrieved 2015-07-24.
  28. ^ a b "Stephanie L. Kwolek | Chemical Heritage Foundation." Stephanie L. Kwolek | Chemical Heritage Foundation. Web. 8 Nov. 2015.
  29. ^ "Kevlar inventor Stephanie Kwolek dies at 90". Retrieved June 19, 2014.

Further reading

External links

Media related to Stephanie Kwolek at Wikimedia Commons