Chemists have found a method to recycle used tires

A team of chemists found an innovative method to break down and melt the rubber that comes from used car tires, a new and efficient method to recycle rubber compared to existing methods that until now were expensive, challenging and ineffective

[Translation by Dr. Nachmani Moshe]

The method, described in an article long ago published in the scientific journal Green Chemistry, addresses the problem of the huge environmental burden caused by used tires, of which nearly three billion were produced and purchased worldwide in 2019. Most of these tires will eventually end up in landfills or massive storage facilities, causing future for the penetration of pollutants arising from them into the ecosystems. In 1990 a massive fire broke out in a pile containing fourteen million scrap tires in Ontario, Canada. The fire lasted for about seventeen days while emitting toxic smoke into the environment, and led to the evacuation of four thousand residents from their homes. The smoke from this fire has been linked to many long-term health problems, including various types of cancer, among firefighters who worked at the scene for many days.

Tires are a typical example of a single-use product from a non-renewable source. Although some of them are used as fuel in the cement industry or broken down into chips that are used as fillers in asphalt, cement or artificial surfaces, there is currently no convenient method for recycling the petroleum-based polymers that make up the tires, so that they cannot be used, recycled or repurposed. "The chemistry of tires is extremely complex and does not allow for easy disassembly, and for very good reasons," says Michael Brook, a professor in the Department of Chemistry and Chemical Biology at McMaster University in Canada. "The features that give tires their stability and durability for use on the road are the ones that also make them particularly difficult to unload for recycling." It was Charles Goodyear who first developed the method of vulcanizing tires back in 1850 by combining sulfur with natural rubber, a combination that creates bridges between the natural polymers and turns the mixture from a liquid into a solid and stable rubber.

In the framework of the new article, the researchers describe a process for the efficient decomposition of the polymeric oils by breaking the sulfur-sulfur bonds with the help of silicon-based materials. The lead researcher compares this structure to a piece of fishing net. "We found a method to cut the horizontal knots so that instead of getting a net, we have a large number of ropes that can be isolated and recycled more easily," he explains. The new method could help reduce and even prevent the significant environmental concerns and dangers that come from piles of used tires.

Although it looks promising on the surface, the researchers warn that the new method has several limitations due to the fact that it is expensive for industrial applications. "We are still investigating the process, but this is only the first step in the revolution. This process brings us closer to a situation where we can reuse used tires and turn them into new products," explains the lead researcher.

The news about the research

for the scientific article