A typical automobile tire is composed of about 30
percent
carbon black, which is a filler that adds durability to the
rubber. Carbon black is petroleum-based, however, meaning that
it isn't entirely eco-friendly to manufacture. That's why Ohio
State University scientists led by Katrina Cornish have been
experimenting with a "greener" and more readily-available
alternative – namely egg shells and tomato skins.
Obtained in the form of food industry waste, the
shells and skins are dried and ground into a powder. When that
powder is added to rubber, it reportedly makes the rubber
stronger while allowing it to remain flexible (by contrast, most
other strength-enhancing additives decrease the rubber's
flexibility).
This attribute is partially due to the fact that the
porous egg shell particles have a large surface area, allowing
for greater contact with the rubber, while the tomato skin
particles remain highly stable at high temperatures, plus they
contain tough fibers.
Katrina Cornish (left) and Cindy Barrera
(right) examine ground tomato skins and eggshells, as well as
samples of rubber(Credit:
Kenneth Chamberlain, The Ohio State University)
In fact, researchers from
Ford and Heinz have been using the skins to manufacture
interior car parts, while scientists at
Tuskegee University have been using shells to make flexible
bioplastics.
According to Cornish, the Ohio State technology
should serve to make tire production more sustainable, it should
reduce American dependence on foreign oil, and it will keep
waste from the food industry from ending up in the landfill. The
tire rubber created thus far is a sort of reddish-brown,
however, so the team is looking into adding black coloring
agents.