How Kevlar Body Armor Works

Kevlar serves as the primary material in the protective equipment used by law enforcement, military and intelligence operatives. However, while Kevlar provides a significant degree of protection, it’s not completely bulletproof or stab-proof, and it does not provide protection against all types of threats or injuries.

      Kevlar Explained

Kevlar is a type of synthetic fiber known as an aramid, created by Stephanie Kwolek at DuPont in the mid-1960s. Kevlar is characterized by its superior strength-to-weight ratio – up to five times stronger than steel, on an equal weight basis. It’s also highly resistant to heat, making it not only strong but also remarkably durable. The material’s unique structure and strength make it effective at dispersing the energy of impact strikes.

      Why Kevlar is Used as Body Armor

Given its unique combination of strength, lightweight nature, and resistance to heat, Kevlar is well-suited for protective applications. Its most common use is in body armor (vests, helmets, gloves etc.), where its high tensile strength helps it absorb and distribute the energy of a bullet, reducing the risk of penetration and consequent injury. This material is similar to tough fabric, making it ideal and relatively easy to manipulate into almost any shape.

      The Science Behind How Kevlar Works

To understand how Kevlar functions as body armor, we need to delve into its molecular structure. Kevlar’s strength comes from its tightly packed, highly ordered molecules. Kevlar molecules form into parallel lines, creating a structure known as a crystalline polymer. These strong bonds between molecules are difficult to break, lending the material its exceptional strength.

When a bullet strikes Kevlar body armor, the layers of fabric spread the impact over a large area, dispersing the energy and significantly slowing the bullet down. This action minimizes the impact of the bullet’s force on a single point, significantly reducing the likelihood of the bullet penetrating the armor. It’s important to note that while Kevlar can prevent penetration, the wearer may still feel the impact and can suffer from blunt force trauma.

In Kevlar vests, many layers of this fabric are tightly woven together. The thickness and the number of layers in the vest determine its level of protection. The more layers, the more energy the vest can disperse, and therefore, the higher the caliber of bullet it can stop. There are 5 levels of NIJ protection levels.

      Other Weapons Against Kevlar

However, Kevlar isn’t effective against all types of threats. For instance, it doesn’t perform as well against edged weapons like knives, which can slip between the woven fibers, or pointed (spikes) weapons that can separate the threads. Similarly, high-powered rounds or armor-piercing bullets can still penetrate Kevlar.

To protect against these type of weapons and more powerful projectiles, additional materials like ceramic or metal plates are often used in conjunction with Kevlar.

      How Kevlar is Made

The production process begins with the preparation of the monomers, namely para-phenylenediamine (PPD) and terephthaloyl chloride (TCl). These monomers are then polymerized or linked together in a solution of sulfuric acid, which serves as the solvent. This reaction results in the formation of the polymer poly(p-phenylene terephthalamide) or PPTA, the chemical name for Kevlar.

Finally, the polymer solution is transformed into fibers through a process known as spinning. This involves forcing the solution through a spinneret, a device equipped with numerous small holes, which shapes the solution into strands as it exits the device.

Kevlar is a remarkable material that has revolutionized personal protection for military personnel, law enforcement officers, and covert operatives alike. Its strength, light weight, and heat resistance make it an invaluable asset in the production of body armor.

Understanding the science behind Kevlar and its limitations is crucial in effectively utilizing and trusting it to protect us in high-risk scenarios. As field operatives, our lives often depend on it.