Bulletproof vests can protect against bullets, but not against expiration? Why do bulletproof vests have a shelf life?
In our opinion, bulletproof vests are a magical tool to protect life safety. Although bulletproof vests are also allowed to be purchased and used in our country, for ordinary people, they are not necessary in the current living environment. For those soldiers who guard the borders and fight on the front line, bulletproof vests are an insurance for their own bodies. But did you know? Bulletproof vests actually have a shelf life!
Nowadays, the bulletproof vests we commonly use are Kevlar bulletproof vests, and the shelf life of this kind of bulletproof vests is generally about 5 years. They also have a shelf life, but the shelf life of Kevlar bulletproof vests is different from that of food. The reason why there is an expiration is that studies have shown that the aramid fiber in the bulletproof vest will begin to show signs of aging after 5 years, and the degree of aging will become more and more serious as time goes by. Because aging will cause its toughness and strength to decrease, and the bulletproof effect will drop sharply. Obviously, soldiers cannot wear such bulletproof vests on the battlefield.
So, wouldn't it be better to replace the aramid fiber? In fact, this is not easy, because as a high-tech synthetic fiber, its density is only one-fifth of the same quality of steel, but its strength is five times that of steel, and it also has very strong toughness, plus the characteristics of high temperature resistance and easy heating. What is the concept at this time? That is to say, a bulletproof vest made of aramid fiber is equivalent to armor made of five layers of steel plates. Ordinary bullets on the battlefield are helpless against it. Of course, if you wear it to experience the power of Barrett, I can only wish you good luck.
In fact, the choice of aramid fiber for bulletproof vests is the result of the survival of the fittest after historical bulletproof vests have tried various materials. At the beginning of the prevalence of firearms in the past, the conception and production of bulletproof vests began non-stop. You must not imagine that the original bulletproof vest actually used Chinese silk as raw material! The raw material used in the first bulletproof vest was actually Chinese silk. The person who developed this bulletproof vest was named Sieglin, a priest in a church.
In our impression, silk is illusory, hazy and beautiful, and a fragile luxury. However, our "bulletproof priest" Casimir Sieglin discovered that silk fibers are extremely strong and elastic, and are the best choice for making lightweight new bulletproof vests at that time. Finally, after continuous attempts, Sieglin weaved four layers of silk fabrics about 3 mm thick and weighing 250 grams per 0.1 square meters in a complex way, and successfully produced a new type of bulletproof vest that could block pistol bullets at close range at that time.
As we all know, silk is a luxury in Western countries, and the cost of using silk to make bulletproof vests is naturally extremely high, so even if its effect was excellent at the time, it still failed to be promoted. So after the start of World War I, all countries surprisingly tacitly chose metal steel to produce bulletproof vests. Such bulletproof vests should actually be regarded as armor. Although they have a certain protective effect, they greatly limit the soldiers' ability to move, and become a burden on the battlefield.
With the precedent of World War I, how to reduce the weight of bulletproof vests became a major focus during World War II. Sieglin's plan was dug out again for research. From silk, cotton cloth to nylon bulletproof materials, although shields have been updated, spears have developed faster. The update and iteration of firearms and weapons made the bulletproof vests at that time retreat step by step. It was not until the 1960s after World War II that bulletproof vests finally re-emerged. DuPont in the United States developed aramid fiber and developed bulletproof vests made of it, which was called "Kevlar bulletproof vests".
Of course, now, Kevlar bulletproof vests are not perfect. It has a shelf life, it cannot wade through water, and it cannot effectively protect against sharp knives. And now we are constantly conducting development experiments to upgrade bulletproof vests to obtain better protection. But in fact, although we who live in peacetime also need to be prepared for danger, who really wants to see bulletproof vests play their role?
