McMaster University chemists have developed a new technique to break down and dissolve the rubber used in automobile tires.
This could lead to new recycling methods that have so far proven to be expensive, difficult and largely inefficient.
Tires are a typical example of a product prepared for a single use from a non-renewable resource.
While some are used as fuel in the cement industry or broken down into crumbs to use as fillers in asphalt, cement or artificial turf, there is no convenient method for recovering the petroleum-based polymers.
That is why they cannot be easily reused, effectively repurposed, or recycled, notes lead author of the study and McMaster professor, Michael Brook.
“The chemistry of the tire is very complex and does not lend itself to degradation – for good reason.”
“The properties that make tires so durable and stable on the road also make them exceptionally difficult to break down and recycle.”
Charles Goodyear first developed the technique of curing tires in 1850 by combining sulfur with natural rubber, which forms bridges between the natural polymers and transforms the mixture from fluid to rubber.
The McMaster team has now developed a new process to efficiently break down the polymeric oils by disolving the sulfur-to-sulfur bond.
Brook likens the structure to a piece of fishnet: “We have found a way to cut all the horizontal lines so instead of having a net, you now have a large number of ropes, which can be isolated and reprocessed much more easily.”
The new method could help eliminate and prevent major environmental concerns and dangers posed by stockpiled tires.
According to Brook, the new method isn’t perfect; it has some limitations because it is expensive for industrial applications:
“We’re working on it, but this is the first major step,” contends Brook. “This process closes the loop on automotive rubber, allowing old tires to be converted into new products.”
Image and content: Georgia Kirkos/McMaster University