The Magic of Kevlar®

As unimpressive as it sounds, Kevlar® is merely just a super-strong type of plastic.

Scientifically known as “poly-para-phenelyne-terephthalamide”, Kevlar® is a para-aramid fiber, and is a member of the synthetic aromatic polyamide family, similar to Nomex®.

The chemical structures of Kevlar® and Nomex® are quite similar, as they both contain many identical molecules which are tightly connected together in long ring-like chains. These run inside, and parallel to the fibers of Kevlar, similar to how rebar is positioned in reinforced concrete.

The chains are then cross-linked with hydrogen bonds in order to form long, thick fibers. This is done by forcing them through a sleeve during a very hot, concentrated state. These fibers are then woven into super stiff mats or sheets, which is what gives the material its super high-tensile strength.

Tensile strength is basically the resistance offered by a material against a force to prevent elongation.

The tensile strength of Kevlar® is about 8 times more than that of a steel wire. Surprisingly it is relatively light in weight for being so strong.

Another benefit of Kevlar® is that it has a very high resistance to both hot and cold temperatures.  It is probably one of the only ‘plastics’ that does not melt or even expand when heated, nor does it become brittle and break at very cold temperatures. Kevlar® is also highly resistant to any kind of abrasions.

Kevlar® and all of its wondrous properties were discovered in the early 1960’s by a US chemist at the DuPont™ chemical company named Stephanie Kwolek (1923-2014). She earned US Patent 3,287,323 for her invention, along with Paul Morgan, in 1966.

Kevlar®, introduced in 1971, was originally developed as a lightweight replacement for steel bracing in vehicle tires, although currently it is used in many things including gloves and even bulletproof vests.

References

Woodford, Chris. (2008/2019) Kevlar. Retrieved from https://www.explainthatstuff.com/kevlar.html. [Accessed (2019-10-26)]

DuPont de Nemous. (2019) DuPont™ Kevlar® Properties. Retrieved from https://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/fibers/articles/kevlar-properties.html. [Accessed (2019-10-26)]

TeamScience ABC. [((2017-July-10) Updated (2019-Oct-19)] What is Kevlar? Why are Kevlar vests bulletproof?. Retrieved from https://www.scienceabc.com/innovation/what-is-kevlar-material-clothing-why-kevlar-armor-vests-bulletproof.html. [Accessed (2019-10-26)]