Kevlar is one of the cutting-edge fiber composites which is known to be exceptionally stronger and unbelievably thin and light like a simple piece of cloth. Given three major types of material composites i.e., Metal, Powder and Fiber, currently Fiber composites are among the most demanding in market for their light weight, cost effectiveness and good mechanical properties. And among all fiber composites like Carbon, Basalt, Flax, Jute, Glass, Kevlar is known to be the most favorable taking its strength and stability in consideration.
Kevlar has unique inter-chain bonds that it gets its strength from. “When it is spun, Kevlar is said to have a relative density of 1.44 and strength of 3260MPa. The inter-chain bonds are formed between NH centers and carbonyl groups and these chain lengths have an effect on other synthetic polymers’ properties like Dyneema. Even in temperatures such as -196 oC (Cryogenic temperatures) Kevlar retains its resilience and strength and to some degree a bit stronger at lower temperatures. Kevlar has a wide range of application from race cars to bullet proof amours etc.” (Hisham, Et al., 2019).
“The Kevlar fibre is prepared as composite material using Epoxy resin in the form of required composite plate and it is compared with the same features of the steel material.
In this process the prepared Kevlar composite material undergone mechanical tests like Impact test, Bending test, Compressive test and Tensile test. Then obtained test results are compared with the results of the steel. This result showed that the Kevlar fibre is strong enough than the Kevlar fibre and also lighter in weight.” (Arunprasad, Et al.,2020)
History and Usage of Kevlar
Scientist Stephanie Kwolek invented Kevlar in 1965 while working at DuPont (the world’s largest chemical company based in America) with a team of a few other scientists while searching for a strong and light weight fiber to replace steel. Kevlar has been used extensively in multiple applications, like making tennis rackets, skis, parachute lines, boats, airplanes, ropes, cables, bullet-proof vests, combat guards for soldiers etc. It has also been used for car tires, fire fighter boots, hockey sticks, cut-resistant gloves and armored cars, protective building materials like bomb-proof materials, hurricane safe rooms, and bridge reinforcements. Very recently, Kevlar has begun to produce stab proof shirts and other cloths for common customers who are prone to attacks or in risky jobs.
Kevlar is generally heat proof to an extent but, if we look into the thermal properties of Kevlar, we find it decomposes with relatively high temperatures (800°F to 900°F [427°C to 482°C] in air and approximately 1,000°F [538°C] in nitrogen), when tested with a temperature rise of 10°C/minute. It loses its weight when it is highly heated in rising temperature and remains flat until getting completely decomposed. It can also be ignited with very high temperatures although burning stops once the heat source is removed. However, very low temperatures have no consequence on Kevlar: DuPont found ‘no embrittlement or degradation’ down to −196°C (−320°F). Like plastics, long exposure to ultraviolet light, for example Sun light can also cause discoloration and damage of the fibers in Kevlar. Kevlar could also be a waterproof material and not affected by moisture.
We must say Kevlar is definitely a new generation consumer product that is no longer just available for industrial work or soldiers but now at a time of so many unrests and criminal activities in society, it is for all of us to use it to have our personal lives safer. Presently we have all kinds of textile products available in market like t-shirts, shoes, gloves, caps, masks, socks and others by Kevlar. So, what could be more interesting and secure than to wear clothes that protect our bodies. Recently the Kevlar textile products have been introduced in European markets and hopefully it reaches to the entire globe very soon.