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In 1965 the DuPont chemist Stephanie Kwolek discovered Kevlar, the fibre now used in bulletproof vests, by insisting on testing a cloudy, runny liquid that a technician did not want to spin. Weight for weight, the fibre that came out was five times stronger than steel.

Wilmington, Delaware, 1965

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The story behind the card

DuPont was looking for a light but strong fibre to replace the steel in car tyres, expecting a fuel shortage. Kwolek's polymer solution came out thin and cloudy, when such solutions were normally clear and thick, and most chemists would have thrown it away. The technician, Charles Smullen, feared it would clog the spinneret, the nozzle that draws liquid into fibre, but she persuaded him. Kevlar reached the market in the early 1970s and is now used in more than 200 products, from body armour and helmets to cables, tennis rackets and aircraft parts. Kwolek assigned her patents to DuPont, as employees did, and in 1995 became the fourth woman in the US National Inventors Hall of Fame. In retirement she tutored students and encouraged young women into science.

Türkçe oku
DuPont kimyageri Stephanie Kwolek, bugün kurşun geçirmez yeleklerde kullanılan Kevlar'ı 1965'te keşfetti. Elde ettiği bulanık, sulu çözeltiyi teknisyen lif hâline getirmek istemedi; Kwolek ısrar etti. Çıkan lif, aynı ağırlıktaki çelikten beş kat daha sağlamdı.
Wilmington, Delaware, 1965

DuPont, bir yakıt kıtlığı bekliyordu ve araba lastiklerindeki çeliğin yerini alacak hafif ama güçlü bir lif arıyordu. Kwolek'in hazırladığı polimer çözeltisi, normalde berrak ve koyu olması gerekirken sulu ve bulanık çıktı; çoğu kimyager onu atardı. Teknisyen Charles Smullen, sıvıyı lif hâline getiren düzeneğin memesini tıkayacağından korktu, ama Kwolek onu ikna etti. Kevlar 1970'lerin başında piyasaya çıktı ve bugün vücut zırhından kasklara, kablolardan tenis raketlerine ve uçak parçalarına kadar 200'den fazla üründe kullanılıyor. Kwolek, çalışanlardan beklendiği gibi patent haklarını DuPont'a devretti. 1995'te ABD Ulusal Mucitler Onur Listesi'ne giren dördüncü kadın oldu. Emekliliğinde öğrencilere ders verdi ve genç kadınları bilime özendirdi.

Sources and further reading

Background reading: Stephanie Kwolek
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