Strengthening rubber with eggshells & tomato peels

About 30 per cent of a typical automobile tire is made of carbon black, a petroleum based filler that makes the rubber durable and gives it its black colour. The number of tires being produced worldwide is going up all the time, which means a lot of carbon black is needed. This material is made by the incomplete combustion of heavy petroleum products, which is bad for the environment. Now, researchers at The Ohio State University have developed a method to replace part of the carbon black in tires with an eco-friendly alternative: waste eggshells and tomato peels.

Eggshells have porous microstructures that provide larger area contact for the rubber and they give rubber-based materials unusual properties. Tomato peels, on the other hand, are highly stable at high temperatures and can be used to generate material with good performance. Another advantage of using egg- and tomato waste is that they allow the rubber to maintain its flexibility, unlike most fillers.

In the United States alone are 100 billion eggs consumed per year, half of which are used in commercial factories. When tomatoes are processed, for example in a can, the peels are removed and discarded, so there is a huge surplus of both materials, which otherwise would end op on the landfill.

The new rubber isn’t black, but rather reddish brown, depending on the amount of eggshell and tomato in it.

According to the researchers, the technology has the potential to solve three problems: it makes the manufacture of rubber products more sustainable, reduces dependence on oil, and keeps waste out of landfills.

While the research is mostly aimed at making tires, perhaps the durable and sustainable rubber can be used in other products as well.

Photos: Kenneth Chamberlain, courtesy of The Ohio State University