sábado, 26 de setembro de 2015

Production Process May Yield Self-Healing Tires



Fri, 09/25/2015 - 8:38am

Greg Watry, Digital Reporter

In the winter of 1839, Charles Goodyear was already experimenting with rubber. He was enamored with the substance, saying “There is probably no other inert substance which so excites the mind.” As the Goodyear Tire & Rubber Company, which neither Goodyear or his family were associated with, tells it, the inventor was displaying his latest gum-and-sulfur formula. In a moment of excitement, he waved the substance in the air, flinging it from his hands. It landed on a nearby stove, and rather than melting, the substance took on a leather consistency.

So goes the story of the accidental discovery.

Today, sulfur vulcanization is the only method for manufacturing automobile tires, making them durable, yet still elastic. However, chemists have discovered a way to bypass the vulcanization step while yielding tire-grade rubber as a result. Further, the tire has self-healing properties.  

Their work was published in ACS Applied Material & Interfaces. The work is the result of a collaboration between the Leibniz Institute for Polymer Research, the Tampere Univ. of Technology and the Dresden Univ. of Technology.     

“Rubber is made of long strand-like molecules tangled and bound together,” according to the American Chemical Society. “When rubber is pierced or torn, critical chemical bonds break and can’t be re-vulcanized, making a damaged tire useless.”

Using the commercially available and widely used bromobutyl rubber, the researchers used a carbon and nitrogen additive, which allows rubber to reform important bonds. When punctured or torn, the rubber recovers the durability and elasticity that usually only results from the vulcanization process.

Tests showed the rubber was capable of healing itself at room temperature. Heating the rubber to 212 F for the first 10 min sped the mending process up. Eventually, a punctured tire may simply call for a car to be left in the garage for a period of time.

After eight days, the rubber tire can withstand pressures at 754 psi, 20 times more than the normal amount of pressure exerted on a tire.

Reinforcing agents, such as carbon black or silica, can further strengthen the product, according to the researchers.   

While a flat tire may not be the bane of a motorist’s existence like traffic, science is taking steps towards making the inconvenience more manageable.


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