Bullet proof vests

 The Defence Ministry has signed a contract with a defence firm for procurement of 1.86 lakh bullet proof jackets for the Army at a cost of Rs 639 crore. The agreement comes nine years after the Army first made a request for more than 1.86 lakh bulletproof jackets. It was not until the plastics revolution of the 1940s that effective bulletproof vests became available to law enforcers, military personnel, and others. The vests of the time were made of ballistic nylon and supplemented by plates of fiber-glass, steel, ceramic, titanium, Doron, and composites of ceramic and fiberglass, the last being the most effective… 

In 1965, Stephanie Kwolek, a chemist at Du Pont, invented Kevlar, trademark for poly-para-phenylene terephthalamide, a liquid polymer that can be spun into aramid fiber and woven into cloth. Originally, Kevlar was developed for use in tires, and later for such diverse products as ropes, gaskets, and various parts for planes and boats. In 1971, Lester Shubin of the National Institute of Law Enforcement and Criminal Justice advocated its use to replace bulky ballistic nylon in bulletproof vests. Kevlar has been the standard material since. In 1989, the Allied Signal Company developed a competitor for Kevlar and called it Spectra. Originally used for sail cloth, the polyethylene fiber is now used to make lighter, yet stronger, nonwoven material for use in bulletproof vests along-side the traditional Kevlar.

A bulletproof vest consists of a panel, a vest-shaped sheet of advanced plastics polymers that is composed of many layers of either Kevlar, Spectra Shield, or, in other countries, Twaron (similar to Kevlar) or Bynema (similar to Spectra). The layers of woven Kevlar are sewn together using Kevlar thread, while the nonwoven Spectra Shield is coated and bonded with resins such as Kraton and then sealed between two sheets of polyethylene film… 

The side of the shell facing the body is usually made more comfortable by sewing a sheet of some absorbent material such as Kumax onto it. A bulletproof vest may also have nylon padding for extra protection. For bulletproof vests intended to be worn in especially dangerous situations, built-in pouches are provided to hold plates made from either metal or ceramic bonded to fiberglass. Such vests can also provide protection in car accidents or from stabbing. 

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