Nano-sized pieces could replace carbon black 100 percent in guayule rubber, she said. (Ms. Cornish also is an expert in guayule rubber, thanks to her previous research both at the U.S. Department of Agriculture's Agricultural Research Service and at Yulex Corp.)
However, nano-sized grind in guayule rubber would be prohibitively expensive, Ms. Cornish said.
Micro-sized grind as a partial replacement in various rubbers is a more viable option, she said.
In any case, the OARDC researchers have their work cut out for them, according to Ms. Cornish.
"We have to match what carbon black can do or exceed it," she said.
In some blends, eggshells and tomato peels can improve rubber properties slightly, such as elongation and softness, depending on what the application calls for, according to Ms. Cornish.
One effect of using eggshells as a partial carbon black replacement is a change in the color of the rubber, according to Ms. Cornish.
Carbon black represents about 30 percent of a tire by weight, and it is responsible for the traditional black color of a tire, she said.