Process uses food waste to help wheels weather wear and tear
Even as the world inches closer to technologies like electric, self-driving cars, we’re not about to stop needing the tires most of our vehicles ride on. Worldwide demand for wheels is putting new pressure on the key ingredients of the average tire— rubber and carbon black. Rubber is sourced from plants, making it’s supply chain a bit easier to sustain. Carbon black has a more limited clock on it, as it comes from partially burnt fossil fuels like coal tar. With that in mind, scientists have been looking for replacements for carbon black, starting in the compost bin.
Carbon black’s role in tire production is as a reinforcing filler. The latex of the rubber brings elasticity and a fair amount of flexibility, but isn’t as strong or durable as most industrial uses demand. Carbon black is then added to reinforce and help manage heat-related stress, making up as much as 30% of the mass of your average tire. It’s also the reason tires are black, contrasting the usually milky white fluid that is collected from rubber-producing plants. Thankfully, carbon black isn’t the only way to strengthen rubber in this manner, which is where some pieces of produce come in.
Support from shells and skins
Researchers at Ohio State University have found that egg shells and tomato peels can be processed into a reliable replacement for carbon black. The eggshells provide porous structures that offer the rubber a lot of surface area to grab onto for internal strength. The tomato peels, partly in thanks to industrial cultivation favoring durable produce, are made of relatively thick fibers that hold up well to the high temperatures a tire is likely to encounter on the road. The only compromise seems to be color, as these food-sourced tires end up being a bit redder in color, rather than the dark, sooty black we’re used to.
Color probably won’t be too much of a worry in the long run, especially when weighing how much easier sourcing these materials will be. Eggshells can be obtained from industrial baking companies that normally pay to have them go to waste in a landfill. Millions of tons of tomatoes are grown and skinned for canning and processing, leaving their skins available for other uses. While most of the world’s rubber is produced in the tropics today, new varieties of rubber-producing dandelions may soon make all the major ingredients for industrial rubber available in a much more renewable manner.
Source: Turning food waste into tires, Scienmag