By Elizabeth Gardner
Small Times Correspondent
April 4, 2002 — You might think an additive that makes plastics lighter, stronger, more heat-resistant and better at keeping foods and beverages fresh would have a large and admiring customer base.
And when it comes to nanoclay, you might be right … eventually. But 20 years after the first patents were filed, things are just beginning to pick up.
The naturally occurring nanostuff, known to geologists as montmorillonite, has its origins
|A step-assist that incorporates a thermoplastic|
olefin (TPO) nanocomposite part made with
Southern Clay Products’ nanoclay is being tested
in this GMC Safari van. General Motors is watching
its performance carefully to analyze whether it can
risk incorporating the material into regular production.
After being purified and then surface-treated so that the flakes will bond to polymers rather than to one another, the clay is sold to plastic resin manufacturers who mix it with pure resins to produce nanocomposites.
Gerardo Lopez, technical manager at Southern Clay Products, estimates the total worldwide annual market for nanoclay at about 100 metric tons, or 220,000 pounds. A typical nanocomposite plastic is only about 3 to 5 percent nanoclay, while more traditional mineral additives can make up 30 or 40 percent of standard plastic composites. So, at current levels, there’s enough nanoclay produced to create roughly 5 million pounds of nanocomposite yearly.
That number could jump to a billion pounds by 2010, said James Morton of Principia Partners, a materials consulting firm in Exton, Pa., that tracks the plastics market. That’s still a small fraction of the many billions of pounds of plastic produced annually, but it could be a solid niche market, Morton said.
“Some say it will revolutionize the next set of plastics, but I don’t believe it,” he said. “Instead you’ll have a new platform of compounds based on this technology. The industry needs to demonstrate a success. That’s the only way you’ll get research and development groups to move forward.”
Nanocor’s Maul acknowledges that things are moving slowly. “There’s not a zooming growth curve here,” he said. “The plastics industry in general is in recession, and automotive and packaging are the drivers for us. And this industry adopts new technology at a fairly slow rate. It’s anybody’s guess how the market will grow.”
Nanoclay lends some intriguing properties to plastic. One of Nanocor’s clients makes plastic piping with built-in herbicide to keep roots from wrapping around it and breaking it when it’s used in underground irrigation systems. Trouble was, the herbicide was leaching out way too fast, depleting itself several years before the systems were scheduled to be replaced. A 5 percent addition of nanoclay slowed the dispersion of the herbicide so that it now lasts for the life of the system.
A layer of nanocomposite in a plastic beer bottle can potentially give the contents a six-month shelf life because the nanoclay flakes prevent air from getting through a plastic film. Spoilage and flavor problems have thwarted widespread use of plastic to bottle beer. Such an application could be a breakthrough for nanoclay, said Morton. One of Nanocor’s customers, Honeywell, is providing nanocomposite plastic to a company that’s developing such a bottle, though the client’s identity is under wraps, according to a Honeywell spokesman.
Another enormous potential market is the automotive industry, where lighter weight and better resilience make nanocomposites an attractive option for trim, bumpers, and perhaps even body panels. General Motors Corp. is testing a thermoplastic olefin (TPO) nanocomposite part made with Southern Clay Products’ nanoclay. It’s a dealer add-on, a step-assist to make it easier to climb into two of the company’s midsize van models, and GM is watching its performance carefully to analyze whether it can risk incorporating the material into its regular production process.
Bob Ottaviani, group manager for the materials and processes laboratory at GM, is optimistic that nanocomposites will start showing up as standard equipment as early as the 2003 model year.
“Per pound, the nanocomposite is more expensive, but you get 18 to 20 percent savings in mass,” Ottaviani said. “On a volume basis it will be competitive with the original material, and we may even see a modest savings.” The substance’s other sterling qualities, including better resistance to scratching, better paint adherence and reduced brittleness at low temperatures, increase its appeal for automakers.
For nanoclay-based composites to really take off, more end users will have to be able to do the same math that GM did and come up with the same result, said Lopez of Southern Clay Products. The raw nanoclay is cheap — 40 to 60 cents a pound. But it needs to be custom-treated to bond with each given type of polymer, and then dispersed into the resin, two expensive processes that boost the cost to $3 or $4 a pound. Even though manufacturers need a lot less nanoclay compared with cheaper fillers, the net cost difference can still add up to 25 percent.
“We could give away the clay and the compounding cost might still be too high,” Lopez said. “You might gain it back in other qualities like lighter weight or better recyclability. To compete with (less expensive fillers) is not impossible, but finding specific applications where the formula comes together takes time.”
Still, the material has captured the imagination of researchers, who are likely to improve it. “The most fascinating thing about it is the way you can use it to put together a set of properties that’s not achievable otherwise,” said Emmanuel Giannelis, materials science professor at Cornell University, whose group has done some development work for Nanocor. Nanoclay can increase both the stiffness and the toughness of a plastic; manufacturers normally expect a trade-off between those two qualities. Some nanocomposites can resist catching fire, unlike their traditional cousins that flame and melt. Others may biodegrade more easily after use.
New discoveries may make nanoclay less expensive to process, says Thomas Pinnavaia of Michigan State University, whose research group is studying the substance and has also worked on projects for Nanocor. “The way you modify the surface of the clay has to be specific to each polymer,” he said. “We are looking at ways to develop more universal modifiers.”
But he doesn’t expect that synthetic nanoscale substances now in development, like carbon nanotubes, will displace nanoclay anytime soon. “What drives industry interest is the initial low cost and the versatile surface chemistry. In some cases you might be able to synthesize specific nanoparticles that would do better, but other times not.”
Both nanoclay companies are financed by parent corporations and neither releases sales figures. But Lopez of Southern Clay Products voices optimism. “As far as the investment curve goes, we’re still in the Valley of Death,” he said. “But we’re climbing the far slope.”
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