All About Kevlar®

We’ve all heard about Kevlar®, a DuPont™ fiber that has made its way into the hands of those in industries ranging from aerospace to law enforcement. This high-strength, highly durable material has numerous applications, making it an ideal fiber for everything from personal protective equipment (where its high strength protects machinists, military, and others) to fiber optic cable (where its flexibility and strength keep optic cables from damage).

What Is Kevlar?

Kevlar is a fiber with incredible strength. Thanks to the way the fiber is manufactured using inter-chain bonds (imagine woven fibers at a microscopic level), alongside cross-linked hydrogen bonds that adhere to these chains (imagine small fibers that span across the surface of those woven fibers, creating a mesh), Kevlar has an impressive tensile strength. In fact, Kevlar is over ten times stronger than steel in tensile strength, pound for pound. Kevlar also has excellent heat resistance, flexibility, ballistic resistance, and cut/puncture resistance.

Tensile Strength

Tensile strength is the maximum stress a material can handle before separating when the material is pulled. Ropes are rated in tensile strength, in order to show how much weight a rope could carry before snapping. Kevlar has a measured tensile strength of about 3,620 megapascals, whereas nylon has a tensile strength of about 75 megapascals (depending on the types of nylon and Kevlar).

Heat Resistance

Kevlar doesn’t lose much strength in extreme colds, nor does it lose strength unless it reaches extremely high temperatures. Thanks to this feature, Kevlar is an ideal material for flame-resistant clothing, including gloves, work clothes, etc. Kevlar can protect against a thermal hazard of up to 800 degrees Fahrenheit, making it ideal for personal protective equipment that is necessary in manufacturing environments where heat be a hazard.


As a fibrous material, Kevlar enables manufacturers to create products that are flexible, yet strong. Kevlar is ideal for clothing applications, since it can be cut and sized into shapes that are form-fitting. Those wearing Kevlar PPE will still enjoy incredible range of motion and they won’t feel burdened by this lightweight, yet highly protective material — workers in a number of industries don’t have to sacrifice dexterity in order to remain protected while on the job. As such, Kevlar is perfect for gloves, protective coats, and more.

Ballistic Resistance

Kevlar is an ideal body armor material, since its fibers are incredibly difficult to break (again, thanks to its tensile strength). The linked chain fibers of Kevlar absorb high-velocity impacts, instead of enabling a ballistic to penetrate the material. This feature makes Kevlar ideal for military and police applications, including body armor and vests. DuPont currently produces a variety of types of Kevlar, including XP and XD Kevlar, which are specifically designed for use as a ballistics material. These materials have even greater strength against ballistics, and the material can be layered and configured as desired to enhance its protective qualities, weight, or flexibility.

Cut/Puncture Resistance

Kevlar cannot be easily cut or punctured, due to the chain links that form the fibers of this material. That means even more protection for police and military applications. In addition, it makes Kevlar the ideal material for a variety of gloves, where workers handle sharp objects. For example, machinists pulling metal shavings off of a production machine won’t have to worry about harming their hands.

How Is Kevlar Manufactured?

Kevlar is a manufactured plastic, and it’s made of a chemical compound called poly-para-phenylene terephthalamide. This chemical is made from creating a chemical reaction between an acid and a chemical solution containing nitrogen and hydrogen. This process results in chemical chains composed of hydrogen, carbon, oxygen, and nitrogen. These chains naturally form small straight “rods” on the molecular level. These chains are incredibly strong on their own.

Once the chemical compound has been made, the resulting solution is then “spun” while the solution is still wet, yet highly viscous. The spinning process orients all of the chains to be parallel, while enabling the hydrogen bonds on the sides of the chain to act as a glue, keeping the chains together. As such, the chains are incredibly strong in tensile strength along the length of the chain, and the hydrogen bonds form incredible tensile strength perpendicular to the orientation of the chains.

When Do Kevlar Vests Expire?

Most Kevlar vests are rated for a service life of 5 years. Afterwards, the material’s strength may be compromised, rendering a vest inadequate for protection. Bulletproof vests and ballistics materials may be damaged more quickly if they are constantly used, used outdoors (where they may be exposed to ultraviolet rays), or not kept clean (since debris may penetrate the material, causing it to weaken). Be sure to check the service life of your ballistics materials and bulletproof vests, and store them to meet the manufacturer’s recommendations, in order to ensure that they don’t deteriorate prematurely.

In addition, Kevlar vests are compromised if they have been struck by a bullet. Since a bullet strike is strong enough to tear fibers (though it may or may not penetrate the material, depending on the caliber of the bullet and the situation), these fibers cannot be repaired, and the material is compromised.

How Can Kevlar Be Reused or Recycled?

While Kevlar may not be strong enough as a ballistics material after half a decade, it may be reclaimed and used for other purposes. The materials of a vest, for example, may be reclaimed and used to create tires, gloves, or other materials. Here at Fiber Brokers, we specialize in breaking down body armor, reclaiming as much useful material as possible, and recycling that material to give it a second service life as a new product. Kevlar is just one of many protective materials that we recycle.

Recycle Kevlar Materials Responsibly With Fiber Brokers

If you have outdated Kevlar vests, or you use Kevlar on your production line and you’re constantly left with scrap, then you can count on Fiber Brokers to recycle your materials responsibly. With expired body armor and ballistics materials, we make sure to track the material throughout the project and we’ll provide you with a certificate of destruction, once your material has been recycled — ensuring that these materials don’t fall into the wrong hands. We also purchase Kevlar scrap from manufacturers, in order to recycle the material and repurpose it into other products. If you’re curious about our Kevlar recycling services, or if you’d like to get started, don’t hesitate to reach out to us!

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