Defatted Soy Flour Eyed as Filler Substitute for
Rubber Tires By Jan
Suszkiw December 24, 2008
In 1941, Henry Ford unveiled a plastic-bodied car whose panels
included soybean meal as component. The feat made headlines--and history--but
the idea never took off commercially. However, researchers continue to toy with
the idea, including Agricultural Research
Service (ARS) scientists
Byars, who are testing soy flour as a "green" filler for tires and other
natural rubber products.
Today's fillers are typically petroleum-based particles called "carbon
black." Tire manufacturers use them in rubber to improve tensile strength and
wear resistance. But petroleum's many competing uses, rising costs and ties to
pollution have rekindled interest in biobased alternatives, especially those
derived from homegrown crops like soybeans.
Soy flour is primarily used in cooking and baking. But Jong and Byars'
studies at the ARS
Products and Food Science Research Unit in Peoria, Ill., indicate the flour
also could serve as an inexpensive alternative to today's carbon-black tire
The researchers use defatted soy flour that's been dispersed in water
to form aggregates 10 microns in diameter (about 1/1000th of an inch). Then
they add the aggregates to rubber latex and freeze-dry the mixture. This causes
the aggregates to form a tight interconnecting network through the rubber.
For lab tests, the researchers mold the soy-based rubber into samples
and subject them to shearing and other forces. Of particular interest is the
"storage modulus," which measures the elasticity of a material. On average, the
storage modulus scores of composites containing 30 percent soy flour are 20
times higher than filler-free rubber, but somewhat lower than those reinforced
with carbon black.
In addition to testing other biobased filler materials, the
researchers are collaborating with rubber manufacturers to further explore the
A report on the research was recently published online in the Journal of Applied
ARS is a scientific research agency of the
U.S. Department of Agriculture.