© OSU — Rubber made from eggshells and tomato skins has a reddish color.
This intriguing food-based alternative to traditional carbon black filler is more sustainable and performs better.
Researchers at Ohio State University have figured out a way to make car tires partially from food waste. An unusual mix of ingredients – eggshells and tomato skins – can replace a petroleum-based filler called carbon black that is usually sourced overseas by American tire manufacturers. Carbon black makes up about 30 percent of a tire, is responsible for its black color, and its cost fluctuates with the cost of oil. It’s getting harder to find as demand for vehicles increases worldwide.
From an OSU press release: “The tire industry is growing very quickly, and we don’t just need more natural rubber, we need more filler, too. The number of tires being produced worldwide is going up all the time, so countries are using all the carbon black they can make. There’s no longer a surplus.”
Dr. Katrina Cornish, who has been working for years to develop domestic rubber sources, is responsible for this latest food-based breakthrough. Cornish explains that her technology solves three problems at once: it makes rubber manufacturing more sustainable; it reduces U.S. dependence on foreign oil; and it keeps waste out of landfill.
Americans eat 13 million tons of tomatoes and 100 billion eggs each year. Tomato product processing plants have piles of discarded skins, which are useful for Cornish’s research because commercial tomatoes are bred to have thick, resistant skins to avoid bruising and are stable at high temperatures.
© OSU — Cornish (left) and Cindy Barrera examine ground tomato skins and eggshells, as well as samples of rubber.
The commercial food industry uses half of the nation’s eggs, which means there’s a steady supply of shells available. Eggshells are good as tire filler because they “have porous microstructures that provide larger surface area for contact with the rubber and give rubber-based materials unusual properties.”
Those so-called ‘unusual properties’ include increased flexibility without compromising durability. Amazingly, the food waste-based prototypes can outperform tires made from standard carbon black, which suggests there’s tremendous potential for further development. The new rubber material is also a reddish-brown color, due to ingredients.
Says Cornish, “We may find that we can pursue many applications that were not possible before with natural rubber.”
The patent-pending technology has been licensed to Cornish’s company, EnergyEne, for further research.