Of the four components tires are generally made from, they typically contain 40 percent rubber. The tire industry consumes about 70 percent of the global rubber supply, and up to 1-billion tires end up as scrap every year. About half of that is used for harmful tire derived fuel (TDF), while another chunk goes to down-cycling, in which tires are ground into rubber crumb to create new products, like flooring mats, roofing shingles, and filler for asphalt.

Many countries continue to use discarded tires as a fuel source, which can be cheap, but also harmful to the environment. In North America, Ontario is the only jurisdiction that bans the use of TDF. TDF is allowed elsewhere because, despite government incentives and subsidies, there is simply not enough market for scrap tire rubber. However, a new technology is tackling this worldwide issue with a sustainable process to make used tire rubber whole again.

Tires and tribulations

Previously, crumb rubber produced by scrap tire recyclers was largely used as a filler in down-cycled products, but the new manufacturing process can use it as a starting material to make tire-derived polymer. Tire manufacturers can then use that new material to create new tires, though the polymer can also be used in other applications — like moulding rubber parts for the auto industry.

“Getting tire rubber back into new tires has been an enormous undertaking, because until now, it has not been possible without the use of chemical solvents.”

Sam Visaisouk, CEO at Tyromer, which has developed such a process, admits the tire and rubber industries have been skeptical about rubber devulcanization, based on past failed attempts. A recycling fee has long been added to the purchase price at retail as a way to help dispose of or repurpose the scrap tire, but nothing has really stuck as a way to reintroduce used tire rubber into new tires.

“There have been many band-aid solutions and subsidies, but nothing fundamental,” he says. “For a startup to transition a university invention into an industrial breakthrough capable of solving a global problem, we needed invaluable support from the University of Waterloo, Ontario Centres of Excellence, Ontario Tire Stewardship, and most importantly, AirBoss.”

New-look rubber

“The process uses supercritical carbon dioxide in an extruder to continuously convert scrap tire rubber crumb into an elastomeric devulcanized rubber strip,” says Visaisouk. “To the tire industry, getting tire rubber back into new tires has been an enormous undertaking because until now it has not been possible without the use of chemical solvents.”

Devulcanization also happens rapidly, averaging about three minutes, with a very high efficiency and low energy consumption to make it cost-effective. In other words, while the reuse of old tire rubber is the primary goal in helping a huge industry tackle a global problem, the process of making the rubber strips is also chemical-free and environmentally friendly.