Inside Materials – Kevlar
The ballistic material par excellence that combines strength, tenacity, and lightweight.
In the 1960s, amid a petroleum shortage, chemist Stephanie Kwolek created Kevlar to replace steel in tires. However, its strength and lightweight nature quickly appealed to various industries. Today, Kevlar is the material of choice for bulletproof vests and helmets.
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Discovering Kevlar
Kevlar is a highly resistant synthetic aromatic polyamide. Its crystalline molecular structure, reinforced by hydrogen bonds, gives it outstanding and unique mechanical and thermal properties.
This synthetic polymer has exceptional tensile strength, up to 10 times stronger than steel at the same weight. Its fibers are spun so tightly that they are almost impossible to separate, giving it high ballistic and shear-cutting resistance. Moreover, it has a heat resistance of up to 425ºC. When exposed to fire, Kevlar does not melt, drip, or produce gases that promote combustion.
Types and Applications
Currently, companies manufacture various grades of Kevlar for specific applications. The most common are:
- Kevlar 29: Used for ballistic protection in body armor, helmets, and car armoring.
- Kevlar 49: Used in structural applications like reinforcement in composites, ropes, and cables.
- Kevlar 119: Used in fiber optics and industrial fabrics due to its high elongation properties.
- Kevlar 129: Used for ballistic protection but offers greater performance.
- Kevlar XP and AP: Advanced types of Kevlar are also used for ballistic protection but are more flexible and lightweight.
Manufacturers also use Kevlar in its various grades in the aerospace and automotive industries to reduce weight while maintaining strength and durability. They also use it in sports equipment, conveyor belts, protective gloves, and gaskets.
Kevlar applications. Courtesy of reamou.
Sustainability: Recycling Strategies
Kevlar’s high resistance is a technical advantage but poses a sustainability challenge. This polymer is not biodegradable and its incineration or disposal in landfills has serious health and environmental consequences. Therefore, recycling is the best eco-friendly solution for this type of material. Through recycling, companies can recover valuable materials and give them a new purpose.
In the case of body armor, one of the biggest applications of Kevlar, there are current initiatives that have emerged to recycle ballistic materials:
- Ballistic Recycling International: Specializes in the certified destruction and recycling of body armor. The company transforms ballistic materials into automobile parts, sporting goods, and flame-retardant clothing.
- Fiber Brokers International: Focuses on the safe destruction and recycling of ballistic and non-ballistic materials. They use the recovered fibers from body armor to manufacture brake pads, car tire treads, cut-resistant gloves, and fire hoses.
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Future Outlook and Industry Leaders
This material will continue to excel in a wide range of industries. Its remarkable mechanical, ballistic, and thermal properties ensure that Kevlar remains the first choice for multiple applications. The global Kevlar fiber market is projected to reach $653.4 million by 2031. This growth will be driven by companies such as DuPont, CTech LLC, MiniFIBERS Inc., and Kolon Industries. Each of them seeks to meet the demand for protective, flexible, and durable products.