(From the July 9, 2012, issue of Rubber & Plastics News)
EAST LANSING, Mich.—A Michigan researcher is developing a more environmentally friendly means of manufacturing automobile tires without using natural rubber or isoprene derived from oil.
Tom Sharkey, chairman of Michigan State University's biochemistry and molecular biology department, is developing bio-isoprene in a laboratory. He's had success in the lab, but developing the process on a commercial scale remains a challenge.
“It's one of those things,” Sharkey said. “It could happen soon, or it could take a while. It could be as soon as two years from now we would have something running making isoprene for tires, but it's more likely four to five years.”
Currently, the majority of automobile tires are made of NR from latex-bearing trees, he said. Researchers also have made isoprene from oil to use in manufacturing tires. However, Sharkey wants to produce a synthetic version of isoprene that would offer several environmental and conservation benefits.
“No. 1 is replacing that oil source, and No. 2, you wouldn't have to have the large plantations of rubber trees or the pressure to increase the acres for rubber trees,” Sharkey said. “Rubber trees were introduced to Southeast Asia and are being farmed there in intensive agriculture. You wouldn't need to have that.”
There is a growing demand for tires globally as automobiles become more common in other parts of the world, he said.
“I think the most important part of it is that the supply of rubber is precarious, and it's more of a supply security issue,” he said of the need for his technology. “As the demand for rubber goes up, as more people—in China, for example—drive cars, we need to make sure we have diverse sources of isoprene and rubber. That's where this would be most important.”
Trees and plants—not just rubber trees—produce isoprene, Sharkey said. However, the naturally produced isoprene is too dilute to be useful commercially.
“So, what I've done is to take the enzyme in the tree that is the last step and some of the other enzymes involved and we put them into bacteria, and now the bacteria make isoprene, but in a way that you can easily capture it,” he said.
Sharkey said he's developed several lines of bacteria that make a “reasonable amount” of isoprene on a lab scale. So far he hasn't produced enough isoprene to make tires on a commercial scale.
“What I'm still doing is tweaking the enzymes, trying to find enzymes that will be more and more efficient so more of the resources we put in get converted to isoprene and the conversion happens faster,” he said.
Tire companies, including Goodyear, have expressed interest in the technology.
However, Sharkey said he is in competition with other companies also working on the technology. He previously published his findings, which companies now are using to try to refine the technology themselves.
While the greatest benefit might be for the tire industry, the same technology could also be useful in producing other rubber products, according to Sharkey.
“For example, latex gloves, rubber gloves, many people have allergies to some of the things in the gloves when the latex comes from the tree,” he said. “But the rubber we would produce from this bio-isoprene should be completely free of allergens.”
Manufacturing isoprene in a laboratory also would reduce carbon emissions normally associated with producing rubber products, Sharkey said. The process would take in carbon dioxide and discharge bio-isoprene using only sunlight as an energy source, according to material published by the university.
Sharkey's research, which is funded in part by the National Science Foundation, is featured in a recent issue of the science journal “International Innovation.”