McMaster chemists find new way to break down old tires into material for new ones

January 13, 2020

A team of chemists at McMaster University has discovered an innovative way to break down and dissolve the rubber used in automobile tires, a process which could lead to new recycling methods that have so far proven to be expensive, difficult and largely inefficient.

The method, outlined in the journal Green Chemistry, addresses the enormous environmental burden posed by tires, approximately 3 billion of which were manufactured and purchased worldwide in 2019. Most of those will end up in massive landfills or storage facilities, ultimately leaching contaminants into the ecosystem.

In 1990, a massive fire continued to burn out-of-control in a pile of 14 million scrap tires near Hagersville, Ontario. It continued for 17 days, spewing toxic smoke into the environment, and drove 4,000 residents from their homes. The fire has been linked to many long-term health issues, including rare cancers among the firefighters who worked on scene for days.

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 from which they are made so they cannot be easily reused, effectively repurposed, or recycled.

"The chemistry of the tire is very complex and does not lend itself to degradation - for good reason," says Michael Brook, a professor in the Department of Chemistry & Chemical Biology at McMaster and lead author of the study. "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.

In the paper, researchers describe a process to efficiently break down the polymeric oils by breaking 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," he says.

The new method could help to eliminate and prevent the major environmental concerns and dangers posed by stockpiled tires.

While promising, researchers caution that the new method has some limitations because it is expensive for industrial applications.

"We're working on it, but this is the first major step. This process closes the loop on automotive rubber, allowing old tires to be converted into new products," says Brook.
-end-


McMaster University

Related Chemistry Articles from Brightsurf:

Searching for the chemistry of life
In the search for the chemical origins of life, researchers have found a possible alternative path for the emergence of the characteristic DNA pattern: According to the experiments, the characteristic DNA base pairs can form by dry heating, without water or other solvents.

Sustainable chemistry at the quantum level
University of Pittsburgh Associate Professor John A. Keith is using new quantum chemistry computing procedures to categorize hypothetical electrocatalysts that are ''too slow'' or ''too expensive'', far more thoroughly and quickly than was considered possible a few years ago.

Can ionic liquids transform chemistry?
Table salt is a commonplace ingredient in the kitchen, but a different kind of salt is at the forefront of chemistry innovation.

Principles for a green chemistry future
A team led by researchers from the Yale School of Forestry & Environmental Studies recently authored a paper featured in Science that outlines how green chemistry is essential for a sustainable future.

Sugar changes the chemistry of your brain
The idea of food addiction is a very controversial topic among scientists.

Reflecting on the year in chemistry
A lot can happen in a year, especially when it comes to science.

Better chemistry through tiny antennae
A research team at The University of Tokyo has developed a new method for actively controlling the breaking of chemical bonds by shining infrared lasers on tiny antennae.

Chemistry in motion
For the first time, researchers have managed to view previously inaccessible details of certain chemical processes.

Researchers enrich silver chemistry
Researchers from Russia and Saudi Arabia have proposed an efficient method for obtaining fundamental data necessary for understanding chemical and physical processes involving substances in the gaseous state.

The chemistry behind kibble (video)
Have you ever thought about how strange it is that dogs eat these dry, weird-smelling bits of food for their entire lives and never get sick of them?

Read More: Chemistry News and Chemistry Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.