Kevlar Case

Kevlar

A. Kevlar strength

In order to understand why Kevlar is such a strong material, it is important to realize that Kevlar is a polymer. Its immense strength comes from its regular internal structure and composition. Kevlar, like all other polymers, is made up of multiple identical basic units, called monomers. Each of these units is like a link in a long chain, and it is attached to other links, or monomers. The Kevlar monomer contains amide groups attached to a phenyl group at opposite ends corresponding to carbon atoms 1 and 4. The chain-like structure is given by the trans- configuration, in which hydrogen bonding occurs regularly, creating a lattice similar to the lattices found in crystals. Thus the Kevlar fibers are almost flawless, extremely strong, and hard to break. This can be seen in Figure 1c, which is a false color X-ray of a Kevlar fiber.

B. Limitations of Kevlar

Kevlar’s main limitation is its inability to withstand UV radiation, its poor performance in environments with high humidity, and its interaction with the chemicals present in human perspiration.

However, Kevlar is not indestructible. One of the factors that can impede and degrade its performance is ultraviolet light. The degradation is small though, only the outside layer is affected and not the inside one. Even the performance is not affected too much; the Kevlar retains most of its strength and rigidity.

It is extremely resistant to punctures and tension because it is woven so strongly. It is also resistant to chemical products and shrinking. It conducts very little electricity. Since this polymer is so durable, it can't be torn either.

They consist of a carrier, plastic film and Kevlar. In order to be successful at stopping projectiles, there must be layers of material. These layers are made of Kevlar