Harvard Researchers Develop Tougher and More Sustainable Natural Rubber for Tires
Researchers at Harvard University have developed a new method for processing natural rubber that could lead to tougher, longer lasting and more sustainable tires.
The research, led by engineers at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS), describes a way to reinforce natural rubber while preserving its long molecular chains, which are responsible for the material’s elasticity, flexibility and crack resistance.
Natural rubber is widely used in heavy-duty tires for trucks, buses and aircraft, but conventional manufacturing methods require reinforcing particles such as silica or carbon black to be mixed into the material using high-intensity processes. According to the researchers, those methods damage the rubber’s polymer chains, reducing durability and contributing to cracking and wear over time.
The new study, published in Proceedings of the National Academy of Sciences, presents a solution-based mixing process that avoids this damage. The team dissolved natural rubber latex in toluene to create what researchers described as a uniform “rubber soup,” allowing silica particles to be mixed into the material without breaking the long chains.
Comparison of conventional and solution-based processing methods for silica-reinforced natural rubber. The new low-intensity mixing process preserves the rubber’s long polymer chains.
Tests showed the resulting material combined high stiffness with significantly improved toughness. Researchers reported that the material’s toughness increased from around 2 kilojoules per square meter to approximately 44 kilojoules per square meter while maintaining a stiffness of about 19 megapascals.
The researchers believe the technology could help reduce waste and tire dust pollution by extending tire lifespan.
“Waste can come in the form of these tire dust particles, and it can come in the form of just throwing tires away,” said Matthew Wei Ming Tan, first author of the study and a former Harvard postdoctoral researcher who is now an assistant professor at Nanyang Technological University in Singapore. “We eventually want a circular economy that minimizes waste and cycles materials back into use.”
The study also highlighted the environmental impact of tire wear, which releases microscopic particles containing rubber fragments and additives into air, soil and waterways.
Co-author Yakov Kutsovsky said the development could become increasingly important as electric vehicles grow heavier and place greater strain on tires.
“Electric cars are heavier than ordinary cars, and larger loads on the car is going to make the tires wear out faster,” Kutsovsky said. “So, while the engine and batteries are quite efficient, the tires become a bigger component of energy loss.”
Beyond tires, the researchers said the material could also have applications in industrial belts, seals and soft robotics.
Article Source: Harvard School of Engineering
