Kevlar

Kevlar, like Nomex is also a man-made fiber that was invented by the DuPont Company. Kevlar is five times stronger than an equal mass of steel fiber and it is extremely tough and wear-resistant. It is the perfect example of the power of performance as it is used in many diverse and mission-critical applications. Some of the properties of Kevlar, which was invented in 1965, include: a high tensile strength with low weight, low electrical conductivity and thermal shrinkage, high chemical resistance, high cut resistance, and flame resistance, etc. These properties make it the ideal choice in many applications.

Kevlar is lightweight, flexible and comfortable and it is also very heat resistant as it can be exposed to a temperature of 400 °C without melting. The material was originally intended to replace the steel belts in tires. Because of its excellent properties, Kevlar is used in a variety of environments such as: personal safety equipment, hunting apparel, athletic shoes, hiking boots, work gloves , vests , helmets , sleeves , skis, kayaks, racquets and parkas.

Kevlar has also been used as rope material and to secure the airbags of the landing apparatus of the Mars Pathfinder. Thin Kevlar mooring ropes are used on the biggest U.S. Naval ships. Kevlar is used as shrapnel shields in jet engines as protection against explosions. It is also used in sports equipment, high-tension drumhead applications, animal handling protection, composite aircraft construction, fire suits, yacht sails, and as an asbestos replacement.

The most common use of Kevlar however, is in the making of bulletproof armor for police forces and the military. Kevlar body armor is designed to help protect against .30 caliber rifle bullets. The Para-aramid fibers of Kevlar do not rust and corrode, and their strength isn't affected by immersion in water. Because of this, they form a good material for mooring lines and other underwater objects. However, unless they are specially waterproofed, para-aramid fiber's ability to stop bullets and other projectiles is weakened when it is wet.

The primary weaknesses of Kevlar are that it decomposes under alkaline conditions and when it is exposed to chlorine. While Kevlar can possess a great tensile strength, sometimes in excess of 4.0 GPa, like most other types of fibers it tends to buckle in compression.

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