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  • Level: GCSE
  • Subject: Maths
  • Word count: 1230

Stephanie Louise Kwolek - The inventor.

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Stephanie Louise Kwolek is one of the most respected chemists of high performance textiles. She is a female chemist who discovered Kevlon. Stephanie Kwolek was born July 31, 1923 in New Kensington, Pennsylvania. In 1964, her supervisor had asked her and her coworkers to search for new high performance fibers. During one of her experiments to find a new synthetic fiber, Stephanie was experimenting with two polymers that just would not melt. The mixture of the solvent and polymers was cloudy instead of clear. She had these new polymers tested and to her amazement she had just invented a new polymer. She had discovered a new fiber, called an aramid fiber, and a new type of substance, called liquid crystalline solution, Stephanie Kwolek had discovered Kevlar.

Kevlar is a polymer containing aromatic and amide molecular groups. It weighs very little but is strong and stiff and is five times stronger than steel. It is resistant to wear corrosion, fatigue, and flame and is nonconductive. Under water, Kevlar is 20 times stronger than steel. It took ten years between the time Stephanie first stirred the test tube that made this new polymer to the time bullet proof vests were made with Kevlar.

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Kevlar brand fiber, first developed in 1965, was the first material identified for use in the modern generation of concealable body armor. Kevlar is a manmade organic fiber, with a combination of properties allowing for high strength with low weight, high chemical resistance, and high cut resistance. Kevlar is also flame resistant; does not melt, soften, or flow; and the fiber is unaffected by immersion in water.

Kevlar 29, introduced in the early 1970s, was the first generation of bullet resistant fibers developed by DuPont and helped to make the production of flexible, concealable body armor practical for the first time. In 1988, DuPont introduced the second generation of Kevlar fiber, known as Kevlar 129. According to DuPont, this fabric offered increased ballistic protection capabilities against high-energy rounds such as the 9mm FMJ. In 1995, Kevlar Correctional was introduced, which provides puncture resistant technology to both law enforcement and correctional officers against puncture type threats.

The newest addition to the Kevlar line is Kevlar Protera, which DuPont made available in 1996. DuPont contends that the Kevlar Protera is a high-performance fabric that allows lighter weight, more flexibility, and greater ballistic protection in a vest design due to the molecular structure of the fiber.

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It is a very tough fiber and it is used today to make products, like bulletproof vest. The discovery of this product has made a big impact on people’s everyday lives.

Kevlar is a long chain-like molecule known as a polymer, which consists of repeating units called monomers. A Kevlar fiber is an array of molecules oriented parallel to each other like a package of uncooked spaghetti. This orderly, untangled arrangement of molecules is described as a crystalline structure. A manufacturing process known as spinning, which involves extruding the molten polymer solution through small holes, obtains crystallinity. The Crystallinity of the Kevlar polymer strands contributes significantly to Kevlar's unique strength and rigidity.

Kevlar is a polyaromatic amide. That is, it contains aromatic and amide groups. Other polymers with a high breaking strength often contain one or both of these molecular groups. image15.pngimage03.png

















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