How Does a Bullet-Proof Vest Work?

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.  

MORE VIRUTALLY RICK:

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!