Parthenium argentatum or Taraxacum kok-saghyz. Which has the better chance of becoming the accepted alternative to traditional natural rubber, Hevea brasiliensis?
Guayule, a desert shrub native to Mexico and southwestern U.S., and TKS, a Russian dandelion and close relative of the common dandelion indigenous to Uzbekistan and Kazakhstan, show considerable promise, according to corporate executives, scientists and academics involved in the research and development of the plants.
"There's potential for both to come to market," said Chuck Yurkovich, vice president of global technology for Cooper Tire & Rubber Co. "Guayule is a little further along in the process, but both have potential."
Guayule and Russian dandelions are subject to extensive development work today. The object is to create hardy seeds, improve rubber yield per plant, cultivate fields large enough to support commercialization and produce sufficient quantities of tire-grade natural rubber to provide a viable substitute to latex tapped from Hevea trees, mostly in Southeast Asia.
Both plants were enlisted to aid the Allied effort during World War II, when the Japanese seized the Southeast Asian rubber plantations. The push toward synthetic rubber ended all research activity in guayule and TKS for decades. But worries about skyrocketing petroleum prices and diseases in Hevea trees has ignited renewed interest in the alternative plants.
"Leaf blight wiped out the rubber trees in Brazil, and white root disease could have the same effect in Southeast Asia," said Hiroshi Mouri, president of the Bridgestone Americas Center for Research and Technology in Akron.
Changing weather patterns in Southeast Asia are also a concern, according to Mouri. "There have been bad floods there the last couple of years, and they messed up both production and transportation," he said.
The rise of Hevea alternatives
Using guayule as a source of NR dates back to the beginning of the 20th century, and TKS about 15 years later, with various fits and starts. Interest in the plants was revived in the late 1980s when allergies from exposure to Hevea latex became a worldwide issue.
The Agricultural Research Service of the U.S. Department of Agriculture began research on guayule in 1989 as an alternative to Hevea latex, and in the 1990s patented an extraction process for hypoallergenic latex from the plant.
Enter Yulex Corp., founded in 1997 and the sole licensee of the ARS process.
Yulex set out to commercialize hypoallergenic guayule latex for medical devices. In 2011, Ansell Ltd., the world's largest maker of medical gloves, bought a majority interest in Chandler, Ariz.-based Yulex and signed an exclusive agreement with the firm.
Several months later Yulex began collaborating with Cooper Tire on developing tire-grade guayule rubber, and in February cut a deal with Italian elastomers manufacturer Versalis S.p.A. to establish a guayule elastomer factory in southern Europe by 2016.
"We are moving forward with consumer products as part of our business plan," said Yulex CEO Jeffrey Martin.
While Yulex has been making other news—giving a $3 million research grant to the University of Arizona and providing the material to Patagonia Inc. for the first all-guayule wetsuit—most of its efforts today are centered on developing tire-grade guayule rubber, Martin said.
Yulex and Cooper are partners with the Agriculture Resource Service and Arizona State University in the Biomass Research and Development Initiative, created last year via a $6.9 million grant.
The joint research project aims to develop tire-grade guayule biopolymers as well as feedstocks, biofuels and bio-based products from guayule plant residue.
Yulex has produced a number of guayule rubber samples that Cooper is evaluating, according to Yurkovich.
"We are working with Yulex to produce a specification for guayule that could be used in tires," he said.
Yurkovich noted Apollo-Vredestein Banden N.V.'s announcement last year that it had made prototype tires using NR sourced from guayule and Russian dandelions.
"But Apollo just put a little rubber in the tread," he said. "We are not just adding something, but literally replacing all synthetic and natural rubber in the tire with guayule."
Apollo-Vredestein has done more than just add a small amount of alternative rubber to the tread, according to a company spokeswoman. She said the firm replaced all the NR in the tread compound—about 25 percent of the total in that mixture—with guayule and TKS rubber.
Apollo-Vredestein has completed all performance testing on the guayule and TKS tires, she said. The prototype tires had better wet grip than traditional tires and comparable high-speed performance, and also higher rolling resistance, according to the spokeswoman.
Apollo-Vredestein is participating in projects to produce commercial quantities of guayule and TKS rubber, she said.
Breaking ground on new center
Meanwhile, Bridgestone Americas—the tire maker with the longest ongoing involvement in guayule, going back to the 1980s work at Firestone—broke ground May 16 at its Biorubber Process Research Center in Mesa, Ariz. The company projects its first guayule rubber samples for evaluation as a component in tires will be ready by mid-2015.
"We are focusing on both agriculture and processing," said Bill Niaura, director of new business development for Bridgestone Americas.
"We need to know how guayule slots in with Hevea and synthetic rubber and whether its particular characteristics offer advantages."
Another guayule company is Casa Grande, Ariz.-based PanAridus L.L.C., which last September began offering samples of tire-grade guayule rubber to any rubber industry officials who asked.
PanAridus CEO Michael Fraley said his company has cut the maturation of the guayule plant in half, while increasing yield to the point that an acre of guayule will produce more rubber than an acre of Hevea trees. The firm also recently announced it had doubled its acreage for planting at its headquarters.
"The list of rubber companies that have asked for our samples reads like a Who's Who of the industry," Fraley said. The company plans a new promotional launch in June or July, he said.
In the world of Russian dandelions, Anvar Buranov is possibly their biggest booster.
Buranov has been involved in TKS research and development since 2002 and founded Nova-BioRubber in 2009. He holds a patent for extracting rubber from TKS at ambient temperatures using mechanical forces—no water or solvents.
Buranov, CEO and president of the Vancouver-based company, said he has the only patented process for TKS rubber extraction. It is not only a much "greener" process for TKS than any other developed to date, he said, but it is also extremely economical—only $1 per kilogram of rubber produced.
"The process developed in 1940 uses a lot of chemicals that are bad for the environment," Buranov said. Put into today's monetary values, that would cost at least $200 per kilogram.
Currently, Nova-BioRubber is concentrating on producing high-quality TKS seeds at acreage it leases near Kamloops, British Columbia. There are hundreds of thousands of acres in Alberta, Saskatchewan and other parts of northern Canada that would be available cheaply and are ideal for growing Russian dandelions, according to Buranov.
"In Alberta or Saskatchewan, you can buy 60,000 hectares of land for $10,000," he said.
Another startup company looking to commercialize Russian dandelions is Carlsbad, Calif.-based Kultevat L.L.C. The company was founded in 2008 by Daniel R. Swiger, founder and former president of Yulex.
Kultevat recently signed a development agreement with KeyGene N.V., a Dutch biotech company; hired Roger Beachy as chief scientific officer; and announced it is moving its headquarters to St. Louis, where Beachy will set up an analytical laboratory for TKS rubber research.
Swiger could not be reached for comment.
Many involved in the development
The Program of Excellence in Natural Rubber Alternatives—a TKS research consortium based at the Ohio Agricultural Research and Development Center at the Ohio State University-Wooster campus—is the major engine powering Russian dandelion research today.
Besides the OSU ag center, collaborators in PENRA include Cooper, Bridgestone Americas, the ARS, Veyance Technologies L.L.C., the Ohio BioProducts Innovation Center, Oregon State University and the University of Akron.
The consortium started up in 2005 and adopted the PENRA name in 2008. Its work on TKS incorporates plant development and varieties, agronomics and processing capability, according to a source close to the work who asked to remain anonymous.
"One thing we bring to alternative rubber research is the breadth of the work we're doing," he said. "The issue is that, due to economic development in China and India, there is a significant worldwide shortage of natural rubber. The need for natural rubber alternatives has become urgent."
PENRA scientists at Ohio State and Oregon State universities have achieved excellent results with Nova-BioRubber's seeds, according to Buranov.
"They achieved 16 percent rubber content in nine months, whereas with guayule, you have 4 percent rubber content in three years," he said.
Although the PENRA website stresses TKS, the consortium also conducts research and development in guayule.
In September 2010, Katrina Cornish joined OARDC as a research scholar with an endowed chair in bio-based emergent materials.
The scientist in charge of developing the method of extracting hypoallergenic latex from guayule at ARS, Cornish later served as senior vice president of research and development at Yulex. Cornish was unavailable for comment.
Agronomics, including plant breeding and seed selection, comprise much of the TKS work at Ohio State, Oregon State, and the University of Guelph in Ontario. The University of Guelph is not a PENRA member but has research ties to PENRA-member universities.
Oregon State began its TKS program in mid-2007 under the late Daryl Ehrensing, according to Rich Roseberg, an associate professor and research agronomist at Oregon State's Klamath Basin Research and Experiment Center.
Ehrensing did a great deal of work in TKS plant selection, according to Roseberg. Some of those plants were used to start TKS breeding at Ohio State, he said.
"My main interest is agronomics," Roseberg said. "I work on all the questions involved with trying to grow the plant—does it need irrigation, what sort of herbicides can it tolerate."
Dave Wolyn, a plant breeder at the University of Guelph, has been addressing fundamental breeding questions for TKS since 2011.
"One problem with TKS is low germination when it's grown in a field," Wolyn said.
"Normally dandelion seed falls into a thatch of grass, which is the perfect place for it to germinate. Our challenge is to achieve a high level of TKS germination in a bare field."
The same climate change issues that plague Southeast Asia also create problems in the rest of the world, which is why Bridgestone Americas is investigating both guayule and TKS, according to Mouri.
"If anything happens to Arizona, we'll still have Ohio, and vice versa," he said.