Stephanie Kwolek was born in New Kensington, Pennsylvania in 1923. As a child Stephanie wanted to be a doctor but was also keenly interested in science. She attended the women’s college, which formed part of Carnegie Mellon University in Pittsburgh, and gained a Bsc in Chemistry in 1946. Due to a lack of funds for a medical course she took up a research position at the Dupont textile fibres laboratory in Buffalo, New York.In 1950 she moved to the new Research Laboratory in Wilmington, Delaware. Here she specialized in low-temperature processes for the preparation of condensation polymers, trying to create highly rigid and strong petroleum based fibres.
Her early successes included the patented Kapton and Nomex aramid fibres, as well as instigating research into liquid crystalline polymers which led to the creation of the first pure monomers used to synthesize polybenzamide.
She took some of the intermediates from these processes which were usually too unstable to remain for more than a few seconds, and created a suitable solvent which allowed for low temperature polymerization of these products. When placed under these conditions the monomers formed a fluid cloudy substance, in contrast to the usually clear and viscous form of most previously discovered polymers.
Kwolek felt however that this substance was worth persevering with and insisted that it was spun into a fibre. The product was an incredibly strong and stiff fibre, the like of which had never been seen before.
Kevlar was first synthesized in 1964 by Stephanie Kwolek at the Dupont laboratories in Wilmington, Delaware in the United States
Stephanie Kwolek’s research with high performance chemical compounds for the DuPont Company led to the development of a Kevlar which is five times stronger than the same weight of steel.
Kevlar, patented by Kwolek in 1966, does not rust nor corrode and is extremely lightweight.
The disadvantages
As strong and light Kevlar is it still has some disadvantages, in its most famous application as a bulletproof material Kevlar is not ideal as it is very stiff and so consequently the wearer suffers a great loss of movement, a great disadvantage when used by police who often need to react quickly.
Kevlar also absorbs water and is consequently more susceptible to environmental influences than some other strong materials such as graphite base materials. Despite it incredible tensile strength Kevlar also has relatively poor compressive properties and so there are still improvements, which can be made.
The future of Kevlar
Kevlar® has evolved over four decades of innovation to do everything from helping save thousands of lives around the world to helping make safer homes and vehicles to helping land spacecraft on Mars.
Kevlar® XP™ a new age!
Both DuPont and independent tests show that Kevlar® XP™ consistently stops bullets within the first three layers of a vest designed with a total of 11 layers. The remaining layers of Kevlar® XP™ absorb the energy of the bullet, resulting in less trauma, or backface deformation, to the vest wearer. Based on DuPont experience, significantly more layers are typically required to stop a bullet in other commercially available lightweight technologies.
Kevlar® XP™ initially will be available for body armor, but DuPont already is developing additional ballistic applications for the future, as well as products for other industries.
Testing Kevlar Vests
Ballistic tests are carried our in a number of different was in a number of countries around the World; each having there own technical specification to work to. What is widely acepted as the "Industry Standard" is the US National Institute of Justice; Body Armor Compliance Testing.NIJ Levels
NIJ levels were develped as a set standard in the US and most Body Armour, Ballistic Plates and Helmets are tested within the set standards.
More information on NIJ Ballistic Standards
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