Armor, a tool used by humans for self-protection in armed conflicts, was also known as armor or armor in ancient times. It is generally made of metal, rattan, or leather and is the last line of defense for soldiers. In modern times, armor has evolved into bulletproof vests. One drawback of bulletproof vests is that if the bulletproof effect is good, the weight is generally heavy, and the bulletproof effect of lightweight bulletproof vests is not good. Therefore, a material with high strength and light weight is urgently needed to improve these shortcomings of bulletproof vests. Kevlar thus entered the military's field of vision. Kevlar is a fiber with ultra-high strength and light weight.
The characteristics of Kevlar are simply tailor-made for bulletproof vests. Kevlar is a yellow, luminous fiber with a density of about 1.43-1.44g/cm³, which is about one-fifth of the density of steel wire, but its strength is five times that of steel with the same quality. It has permanent heat resistance and flame retardancy and can be used for a long time at temperatures up to 160℃. Its strength is almost unaffected when exposed to high temperatures above 300℃ for a short time, only degrading at temperatures above 500℃, and it has good heat dissipation performance.
Kevlar bulletproof vest also has the characteristics of acid and alkali resistance and organic solvent resistance. After soaking in a 10% sulfuric acid solution or a 28% sodium hydroxide solution for 1,000 hours, its strength is almost unaffected, and it is also unaffected in organic solvents. It also has various properties such as anti-static, high wear resistance, tear resistance, and flame resistance. Since Kevlar was discovered by the military as a material for bulletproof vests, it has replaced traditional nylon and glass fibers, and its protective capabilities have increased by more than twice. The weight of Kevlar bulletproof vests is only about 2-3 kilograms, with good flexibility and comfortable wearing. It is now widely popularized worldwide.
Kevlar has developed to today and is not only used to make Kevlar bulletproof vests. Composite armor composed of Kevlar and steel or aluminum plates has been widely used in tanks, armored vehicles, and even aircraft missiles. The overall fuselage of the French Rafale fighter aircraft and the Tiger helicopter is mostly made of Kevlar composite materials, and the rocket engine casing of the US Trident missile is also made of Kevlar fiber-impregnated epoxy resin materials. Not only in military, in civil use, Kevlar also has many good applications, such as special racing suits for racing drivers, high-strength ropes, safety gloves, corrosion-resistant protective clothing, tire manufacturing, and drum materials, etc.