Recycling of whole passenger car tires

Due to the increasing number of vehicles, the ‘mountain’ of used tires has grown dramatically during the last decades. Every year, approximately 800 million scrap tires are disposed off around the globe. Piled up, they would cover a distance of 200,000 km and go 5 times around the world or 2/3 of the distance to the moon. This amount of waste tires is expected to increase by approximately 2% each year.

Since polymeric materials do not decompose easily, disposal of waste polymers including rubbers is an environmental problem. Strategies for dealing with the issue of scrap tires and the best way to recover, recycle and reuse them are global challenges. Recycling of used rubber not only solves the waste disposal problem and reduces the environmental burden; it also saves the valuable and limited resources of fossil feedstock.

The aim of this project is to develop a process that can break the sulfur crosslink network in used tires: the vulcanization process giving the material its final shape and stability is reversed. The recycled material will be used as a high performance raw material for new tires: the shortest possible cycle on the recycling ladder.

Investigations are performed to selectively break sulfur crosslinks and limit polymer chain scission. With the aid of an appropriate devulcanization aid, the balance of polymer/crosslink scission can be shifted to crosslink scission or real “devulcanization”, as indi-cated by the arrow in the graph.

For more information regarding this project, contact S. Saiwari, MSc