Pneumatic tires or tyres are used on all types of vehicles, from cars to earthmovers to airplanes. A significant disadvantage of tyres is the fact that recycling them is not very easy and so mountains on tyres are gathering all across the world.

It may come as a surprise, but the same technique that makes tyres so durable, the vulcanization, makes them hard to recycle. The sulfur bonds between rubber make them almost impossible to reuse, since they don't melt.

Another threat posed by the piles of rubber is their flammability, meaning that a spark could set off a dirty, long-burning fire, which releases heavy metals and other pollutants into the air and soil.

David Isaac and colleagues at Swansea University, UK, have found a new method of recycling rubber using plasma. Their process involves using spinning ground-up tyres, called rubber "crumb", inside a chamber filled with ionized oxygen gas plasma.

"It makes the surface of the crumb much better at sticking onto new rubber," Isaac explains. "Without treatment, the interface between the old pieces and new rubber is very weak."

Treating rubber molecules from fresh non-vulcanized rubber with plasma results in recycled rubber which has similar tensile strength and other mechanical properties to completely new material.

This technique creates reactive oxygen molecules on the surface of the rubber by opening up carbon bonds, which bonds well to fresh rubber if added straight away.

"Around 65% of the world's rubber production is for tyres," said Isaac. "Tyre rubber is recycled into products like flooring, but it makes sense to try and recycle them into more tyres."

The team of researchers at Swansea joined hands with a company operating in the field to develop the new process commercially and interest tyre makers in the new and revolutionary applications.