Original photo by Composite_Carbonman/ Shutterstock
Few synthetic polymers have saved as many lives as poly-para-phenylene terephthalamide, better known as Kevlar. These super-resilient, nylon-like threads are five times stronger than steel, lighter than fiberglass, incredibly heat-resistant, and fantastically flexible. Although the material is found in a variety of items from kayaks to NASA spacecraft, Kevlar has arguably made the greatest impact in bulletproof vests and body armor. But Kevlar’s incredible, lifesaving superpower is only a happy byproduct of its original purpose — creating a new kind of car tire.
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It's a fibKevlar is strong, but it doesn’t outdo nature. In 2019, scientists discovered that the Darwin's bark spider (Caerostris darwini), a Madagascar arachnid, produces silk with a tensile strength 10 times stronger than Kevlar, making it one of the world’s toughest materials.
In the mid-1960s, chemist Stephanie Kwolek was working in a Wilmington, Delaware, research lab for the textile division of the chemical company Dupont, which had invented another “miracle” fiber called nylon 30 years earlier. Fearing a looming gas shortage — one that arrived in earnest in 1973 — Dupont was searching for a synthetic material that could make tires lighter and stronger, replacing some of their steel and improving overall fuel efficiency. One day, Kwolek noticed that a particular batch of dissolved polyamides (a type of synthetic polymer) had formed a cloudy, runny consistency rather than the usual clear, syrup-like concoction. Although colleagues told Kwolek to toss it out, she persisted in investigating this strange mixture closely, discovering that it could be spun to create fibers of an unusual stiffness. Kevlar was born. Dupont introduced the “wonder fiber” in 1971, and the material began undergoing tests in ballistic vests almost immediately. By one estimate, it has saved at least 3,000 police officers from bullet wounds in the years since. Despite its myriad applications, Kevlar still delivers on its original purpose as an automotive component, whether baked into engine belts, brake pads, or yes, even tires.
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Some historians trace the beginning of modern chemistry to the discovery of ______ in 1774.
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Some historians trace the beginning of modern chemistry to the discovery of oxygen in 1774.
The top speed of the world’s fastest cars is mostly limited by their tires.
Rubber tires can only go so fast. The centrifugal force of speeds approaching 300 mph creates an incredible amount of pressure and heat that normal tires just can’t handle. Because of this, supercars such as the $3.8 million Bugatti Chiron can’t reach the top speeds its 1,500-horsepower engine might technically achieve (around the 310 mph mark). This physical limitation is why land speed record-breaking vehicles — which are more like wheeled rockets than cars — get rid of rubber entirely and ride on aluminum alloy wheels instead. Undeterred, the tire company Michelin developed all-new tires for the Chiron, reinforcing the rubber with carbon fiber and testing them with the same equipment NASA used to test the wheels for space shuttles. In 2019, these reinforced tires helped the Chiron reach 304.77 mph — a new speed record for any car with street-legal tires (rocket cars not included).
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
