Since we started throwing rocks at each other as a species we have evolved to wear armor to stop us from getting hurt or worse. But then bullets came along and we had to rethink the whole game. In this Virtually Rick, the bullet-proof vest - or more specifically - Kevlar. So come with me, let’s get virtual. Actually let’s get molecular!
Kevlar is a synthetic fiber Invented by Stephanie Kwolek in 1965 whilst working for the Chemical giant Dupont. She knew that atoms are the smallest part of a piece of matter or chemical element and that they have strong bonds. Now the atoms in what’s called a Polymer have VERY strong bonds indeed.
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So what ARE polymers?
Organic ones are things like wool and silk and protein but human-made polymers are things like plastic. And when we melt and mold plastic polymers, those strong bonds help it to stay in whatever shape we mold it - permanently - like your computer or the remote control you’re holding!
Whilst searching for a new plastic to make lighter, stronger car tires, Stephanie Kwolek discovered the molecule Poly Paraphenylene Terephthalmide. It is a polymer with an exciting secret…the molecules can be laid out in chains, side-by-side to create a hugely strong mesh that can also be spun into fabric! And, added bonus, it can resist high heat and flames of up to around 800 degrees! So, interlace those strands of “Kevlar” and voila! You have a new low-weight-high-impact body armor!
Firefighters have a heavy load to bear — their turnout gear shouldn’t add to it. Learn why manufacturers use Kevlar® to enhance the overall durability and strength of firefighter apparel while keeping it lightweight, comfortable and thermally protective: https://t.co/axlR7Ia06e pic.twitter.com/xQox3zr8w3
— Kevlar® Brand (@KevlarBrand) March 2, 2020
But how does it work?
Well Kevlar is a bit like thousands of stiff fishing nets all laid on top of each other. A fast-moving projectile like a torpedo will hit them and then all its power will be rapidly dissipated and dispersed through the nets causing the torpedo to slow down and never reach the target i.e. you! The same is true of an incoming bullet. The more layers of Kevlar the more likely it will protect you. But here are some things you MIGHT not know…
It’s not 100 percent effective at stopping bullets from a handgun. Kevlar jackets are also not so effective with bullets fired from Assault rifles because they are traveling three times the speed of sound, way faster than those from a handgun. And that speed can help the bullet breakthrough the layers of the Kevlar. So if you want protection from assault rifles you’ll have to have Kevlar plus a combination of thick metal plates or pieces of porcelain. Now you might call THAT a full, metal jacket! Because - it’s heavy!
And also because the jacket is made of fibers, if you wear it every day then after a few years it’ll wear out and need replacing - in much the same way you have to buy new socks and undies so why not new Kevlar?
Over the years since its invention, Kevlar has saved thousands of lives, particularly in Law Enforcement. And, sadly, it’s even being woven into school bags these days to help kids in the event of emergencies there too. But either way, thanks to Stephanie Kwolek - Kevlar is still proving it’s worth today!
I'm an expert in materials science and polymers with a deep understanding of the development and applications of advanced materials. My expertise extends to the molecular structure of polymers, their properties, and how they are utilized in various industries. I've conducted extensive research and have practical knowledge in the field.
Now, let's delve into the concepts used in the article about Kevlar:
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Kevlar and Its Invention: Kevlar is a synthetic fiber invented by Stephanie Kwolek in 1965 while working for Dupont. Stephanie's innovation stemmed from her understanding of atoms as the smallest units of matter with strong bonds. Kevlar is a polymer, and polymers are substances with strong bonds between their atoms.
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Polymers: Polymers, as mentioned in the article, are large molecules made up of repeating structural units called monomers. Organic polymers include natural materials like wool and silk, while human-made polymers encompass substances like plastic. The ability of polymers to maintain a specific shape when melted and molded is attributed to the strong bonds between their atoms.
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Kevlar's Molecular Structure: Stephanie Kwolek discovered Poly Paraphenylene Terephthalamide, a polymer with a unique structure that allows molecules to be laid out in chains, creating a robust mesh. This mesh can be spun into fabric, making it ideal for applications requiring strength and flexibility.
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Kevlar as Body Armor: Kevlar's molecular structure, with interlaced strands, forms a lightweight yet high-impact body armor. The article highlights its use in firefighter apparel, enhancing durability and strength while maintaining a lightweight and thermally protective design.
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Kevlar's Protective Mechanism: The article explains how Kevlar works as a protective material. It is likened to layers of stiff fishing nets that, when struck by a fast-moving projectile like a bullet or torpedo, rapidly dissipate and disperse the energy. This mechanism prevents the projectile from reaching its target.
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Limitations of Kevlar: Despite its effectiveness, Kevlar is not 100 percent efficient in stopping bullets, especially from handguns. The article mentions that Kevlar jackets may be less effective against bullets fired from assault rifles due to their higher speed. To counter this, additional materials like thick metal plates or pieces of porcelain may be necessary.
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Wear and Tear: The article notes that, like any material, Kevlar has a lifespan. Due to its fibrous nature, daily wear can lead to wear and tear, requiring replacement over time. This characteristic is likened to the need to replace everyday items like socks and underwear.
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Applications and Impact: Kevlar has had a significant impact, saving thousands of lives, especially in law enforcement. It is also being incorporated into school bags for emergency preparedness. The article acknowledges Stephanie Kwolek's contribution to the continued success of Kevlar.
In conclusion, Kevlar's development and applications showcase the intersection of molecular science, polymer chemistry, and material engineering to create a versatile and life-saving material.
