A cut or torn tire usually means one thing -- you have to buy a new one. But some day, that could change. For the first time, scientists have made tire-grade rubber without the processing step -- vulcanization -- that has been essential to inflatable tires since their invention. The resulting material heals itself and could potentially withstand the long-term pressures of driving. Their report appears in the journal ACS Applied Materials & Interfaces.
Vulcanization involves adding sulfur or other curatives to make rubber more durable while maintaining its elasticity. But once an errant piece of glass or other sharp object pierces a tire, it can't be patched for long-term use. Researchers are beginning to develop self-healing rubber in the laboratory, but these prototypes might not be stable over time either. Amit Das and colleagues wanted to address that shortcoming.
Using a new simple process that avoids vulcanization altogether, the researchers chemically modified commercial rubber into a durable, elastic material that can fix itself over time. Testing showed that a cut in the material healed at room temperature, a property that could allow a tire to mend itself while parked. And after 8 days, the rubber could withstand a stress of 754 pounds per square inch. Heating it to 212 degrees Fahrenheit for the first 10 minutes accelerated the repair process. The researchers say their product could be further strengthened by adding reinforcing agents such as silica or carbon black.
The authors acknowledge funding from the Deutsche Forschungsgemeinschaft.
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Watch this ACS Headline Science video to see the rubber heal by itself.