General, Research, Technology

What you need to know about Kevlar - a material stronger than steel?

Nature is rich in amazing materials.Take wood, for example: this material is so durable and versatile that it can be used for almost everything - from papermaking to building houses. There is also wool, which allows animals to keep warm at sub-zero temperatures, and leather, a material that can recover from damage in just a few days. However, as incredible as these materials are, they are far from ideal and not suitable for universal use. But is there material that we use on a daily basis? A tough synthetic material with the beautiful name of Kevlar, it is often described as being "five times stronger than steel for equal weight." Interestingly, Kevlar is used both in the manufacture of boats, bowstrings, and in the automotive industry. In this article, we will talk about Kevlar and the reasons why it is so durable.

Heavy-duty Kevlar is known for its applications in body armor and the automotive industry. Used in industrial production since 1971.

Content

  • 1 What is Kevlar?
  • 2 Properties of kevral
  • 3 Kevlar production
  • 4 Where and what is Kevlar used for?

What is Kevlar?

Essentially, Kevlar is a heavy-duty plastic.There are literally hundreds of synthetic plastics in the world, made by polymerization - the chemical process of forming high molecular weight compounds (polymers) from low molecular weight compounds (monomers) that have completely different properties. As for Kevlar, its amazing properties are partly due to its internal structure and the fact that it is made of fibers that are tightly bound together.

Note that Kevlar, a proprietary material made only by the DuPont ™ chemical company, comes in two main varieties called kevlar 29 and kevlar 49 (other varieties are made for special applications). By its chemical structure, Kevlar resembles another universal protective material - nomex.

Kevlar and Nomex are examples of chemicals thatcalled synthetic aromatic polyamides or aramids for short. These synthetic materials are made in a chemical laboratory (as opposed to natural fabrics such as cotton or wool). Like Nomex, Kevlar is a distant cousin of nylon, the first commercially successful “super polyamide” developed by DuPont in the 1930s.

Why not a glove of infinity? Pictured are Kevlar safety gloves from Dupon.

Kevlar was opened in 1964 by an Americanchemist Stephanie Kwolek (1923-2014). Kvolek received a patent for the invention of Kevlar together with Paul Morgan in 1966, and since 1971 Kevlar has been actively used in industrial production. Although Kevlar was originally developed as a lightweight replacement for steel mounts in car tires, today it is known worldwide for its use of body armor and protective gloves.

Kevral properties

As mentioned above, Kevlar is about fivetimes stronger than steel, while being relatively lightweight. It is also interesting that, unlike most plastics, Kevlar does not melt: the material withstands high temperatures and decomposes only at about 450 ° C. Unlike its sister material Nomex, Kevlar is flammable, but usually stops burning when the heat source is removed. Very low temperatures have no effect on Kevlar: Dupon found "no material embrittlement or degradation" down to -196 ° C.

Like other plastics, long-term exposureUltraviolet light (such as sunlight) causes discoloration and some degradation of the Kevlar fibers. This material can withstand attacks from various chemicals, although prolonged exposure to strong acids can destroy it over time.

Kevlar is produced in the form of: technical threads; yarn; roving; fabrics.

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Kevlar production

You probably know that natural materials,such as wool and cotton must be twisted into fibers before being made into useful textiles. The same is true for man-made fibers such as nylon, kevlar and nomex.

There are two main manufacturing stepskevlar. The first is directly related to chemistry - you first need to produce the base plastic from which Kevlar (a chemical called poly-para-phenylene terephthalamide) is made. The direct transformation of a chemical product into a more useful, practical and durable material occurs during the second, final stage of production.

Currently, over 80% of the world's Kevlar is produced at the Chesterfield plant in Spruence. Synthetic fiber is wound on spools as shown here and then processed into other products.

Hot and viscous through a complex processthe poly-para-phenylene terephthalamide solution is passed through a die (a metal former, a bit like a sieve). The result is long, thin, strong and stiff fibers that are wound around drums. The fibers are then cut to length and woven into a tough rug known to us as Kevlar.

See also: What materials can be used to build houses on Mars?

Where and what is Kevlar used for?

Kevlar can be used by itself or incombination with other materials to give them extra strength. This material is widely known, probably due to its use in bulletproof body armor and the Legend Busters show, but it has dozens of other uses. As the original goal of the developers was to create a lightweight, durable fiber that could be used in the production of tires, today kevlar is used in automotiveindustry, but not only. It is known to be used in the manufacture of boats, aircraft and even in the construction industry, although it is not the main structural and building material.