Ohio State making strides in natural rubber alternative

By Steve Dudukovich, Rubber & Plastics News Staff

Wooster, Ohio -- In a greenhouse at Ohio State University's Ohio Agricultural Research and Development Center in Wooster, Ohio, the plant Taraxacum kok-saghyz, also known as the Russian dandelion, is growing by the thousands. It's part of a collaborative effort by several partners to turn the latex harvested from the roots of the plant into a domestic source of natural rubber.

This isn't the first attempt to exploit the TKS plant, native to the former Soviet republics of Kazakhstan and Uzbekistan. In the 1930s and during World War II-when Japanese forces seized the Southeast Asia Hevea rubber-growing region-a similar attempt was made, and the US Department of Agriculture even conducted a feasibility study of growing the plant in this country.

After the war spawned the synthetic rubber industry and NR-growing countries were liberated, interest waned in TKS, which produces a high-quality NR in its fleshy taproot comparable in performance to the rubber extracted from the Brazilian rubber tree, Hevea Brasiliensis.

Today, with record prices for Hevea rubber and huge, oil-related price hikes for SR, there is renewed interest in the plant.

The beginning

The latest work on TKS began in 2005, initiated by Delta Plant Technologies Inc., a start-up aiming to find a domestic source of NR. The firm is partnering with Ohio State University, the University of Akron, Oregon State University, Cooper Tire & Rubber Co., Bridgestone Americas Center for Technology and Research, and the USDA.

When the company was formed by Fred Anderson-a onetime Boeing Co. executive who soon was joined by former Goodyear executives Bryan Kinnamon and John Lawrence-it looked like an NR shortage was brewing, Kinnamon said.

Delta President Kinnamon, a retired vice president of original equipment sales at Goodyear, said throughout his career a rubber shortage always appeared to be around the corner. It never quite happened.

He said that fact means Delta needs to develop an NR that can be profitable at whatever the market price is for natural rubber, not just one that needs a shortage to succeed. To achieve this, various requirements must be met concerning the percentage of rubber in the plants, the tons of biomass per acre, the conversion costs and the cost to grow an acre worth of crop, Kinnamon said.

“Those four parameters really established the framework upon which we've been focusing our development activities for the past four years,” he said. “From an experimental standpoint, we have been successful in exceeding each of those milestones. We have lots of development to do it on a commercial scale, but there should be no unachievable technical obstacles in the way of doing that.”

Domesticating the plant

The botanists involved in TKS essentially are trying to tame a wild plant. It's not easy, according to Matt Kleinhenz, associate professor of horticulture and crop science at Ohio State.

“A weed is built to last generation after generation after generation,” Kleinhenz said. “They often are very adaptable to different environments and so on, but their goal is not necessarily to perform the same way each and every time.”

Kleinhenz compared domesticating a wild plant to getting a dog to do your bidding. In both cases, they must be trained to do the same thing every time.

In agriculture, with corn crops, for example, stalks are the same height and color and the corn grows at the same rate.

To succeed, the TKS plant must achieve this standard. The plants must grow at the same rate, produce roots of the same size that have the same level and quality of rubber, time and time again, Kleinhenz said.

Without these characteristics, farmers wouldn't be interested in growing TKS.

“We are talking about going to hundreds of thousands of acres, so you have to be able to show a farmer that it's going to be profitable to grow this crop versus growing corn or soybeans or something else,” said Fred Michel, associate professor of food, agriculture and biological engineering.

He said besides rubber, the TKS plant produces inulin, which is used in the production of ethanol. That fact is important because it gives farmers more options.

It is Michel's job to extract the rubber from that plants that Kleinhenz is responsible for growing. He said the process, developed in the 1940s, isn't complicated.

The roots are dried and stored, and eventually run through a hot water solution, where inulin is extracted. Roots are then milled and turned into an oatmeal-type substance, which is put through a screen and possibly more milling.

The substance enters a flotation tank. The remaining rubber is extracted and floats to the top and is scraped off, with the leftover material treated as waste.

The rubber is screened again, goes through a continuous centrifuge where all the water is removed, and is dried and boxed for shipping.

Michel said the process extracts 98 to 99 percent of the possible rubber from the roots.

Testing problem

While the project is off to a successful start, and recently received a $3 million Third Frontier Wright Projects grant that invests in research to boost Ohio's economy, some barriers to commercial development remain.

For example, Oregon State University is growing a test crop in the fields of Oregon, but in some crops, Michel said, there isn't enough rubber being extracted.

And while the plants grown in the greenhouse at Wooster produce enough rubber, there aren't enough of them.

That causes trouble for the tyre companies, which need enough material to perform validation tests. The University of Akron also does validation and has the same problem with supply.

Robert Seiple, manager of the applied polymer research center at Akron, said that researchers look for a number of things when validating the quality of rubber, one of which is molecular weight, which must be high.

“If you have a low molecular weight then you lose your strength in the material,” Seiple said.

The staff at Akron tests rubber in a gel permeation chromatography instrument, where rubber separates into molecular weight fractions. This helps researchers know what the distribution is because distribution of molecular weight determines the viability of using the tested rubber in a product, Seiple said.

The researchers also look at the rubber's fatty acid content, since a big range of fatty acids isn't desirable. Too much fatty acids would affect cure time.

The Akron researchers also test the dynamic properties of the material over a temperature and frequency range, Seiple said.

“If you have a high loss in that material, in other words if things start to flow in the time frame that your looking at, if things start to flow, then you lose that elasticity,” Seiple said. “If you would have a material that has bad dynamic properties and you made a tyre out of it, then a lot more of your costs for gas would go into pushing your car down than if it had perfect elastic tyres.”

Seiple believes the NR extracted from the TKS plant could become commercially viable. He said the project is important because it would help wean the U.S. off foreign-grown Hevea rubber. The country's manufacturers spend $3 billion a year on imported NR.

“In the case of a conflict somewhere in the world where the source of that material could be cut off, it would be nice to have our own source of that in U.S.,” he said.

Economic impact and the future

A viable TKS industry would have a positive impact on the agricultural community, Kinnamon said. Extraction facilities, each employing 30 workers, would be established near the rural areas where the crops would grow. Farmers who grow TKS could participate in ownership of the extraction facility that handles their crops.

In five years, Kinnamon said his company would like to be operating a full scale commercial plant. In the long term, the company would like to command about 10 percent of the market, a goal that would require six commercial factories to achieve.

The OSU Ag center hopes to have an extraction operation up and running soon, too. The money received from the Third Frontier grant will go toward building the facility.

From Rubber * Plastics News (A Crain publication)