Researchers of the Brook Research Group at McMaster University in Ontario, Canada, have discovered an efficient and mild process that uses silicone chemistry to break the sulfur-to-sulfur bonds in tires.
As Michael Adrian Brook, professor of chemistry and chemical biology explains, the silicones selectively cut the sulfur-sulfur connections, leaving only organic chains that can be easily isolated and reused to create new products.
The process was originally designed to make new silicones using very small quantities of a catalyst, but looks to be a promising solution for addressing the waste tire problem by enabling recycling of petroleum-based tires.
The chemical process involves cutting the tire into sections and then forming powdered crumb. A mild, rapid reaction produced by heating this material with specific silicones at 100°C for 45 minutes converts around 90% of the available organic materials into a readily processed pale yellow oil.
The remaining substances, including inorganic carbon, silica, metal and polyester cord fibers, are removed by filtration. The oils recovered are very similar in constitution to the virgin polymers found in new tires.
Brook’s team discovered that these materials can also be repurposed. Researchers were able to convert the recovered polymers back into new rubbers, for example. The inorganic residue, initially removed by filtration, could also be reused as a reinforcing agent in the new rubber.
According to Brook, the next step will be to investigate further what products can be made from the recovered polymers and reduce the quantity of catalyst needed to improve the economics of the process.
This story was originally published by The Conversation. Read the full article here.