Technologies involving nanometer-size materials will affect how the polymer industry does business in coming decades, but they are emerging slowly.
A federally funded nanometer initiative, through myriad bureaucracies, has spawned academic and military research, spin-off and start-up ventures and, during 2002 alone, dozens of technical conferences. Some corporate interest is resurfacing.
The science boggles imagination, and the size is miniscule: a nanometer is one-billionth of a meter.
Nobel Laureate Richard Smalley of Rice University discussed one technology, carbon nanotubes, in a May presentation to the Society for the Advancement of Material and Process Engineering. Nanotubes are used as reinforcements to create materials that are strong, lightweight and stiff.
Smalley compared the scale-up potential of nanotubes with what has been ``done for decades with polymers.'' Use a catalyst, grow the material and, ``in principle, [it] could be abundant and cheap,'' Smalley said. His start-up firm, Carbon Nanotechnologies Inc., is establishing a Houston pilot plant to make single-wall nanotubes.
In addition to nanotubes, technologies involve use of clay for some nanocomposites and, separately, polyhedral oligomeric silsesquioxanes. Also, nanofibers exist but are not used in polymers.
Nonreactive organics in each POSS molecule make a POSS nanostructure compatible with polymers, biological systems and surfaces, according to Joseph Lichtenhan, president of Hybrid Plastics Inc. in Fountain Valley, Calif. POSS molecular silicas are compounded into thermoplastics, primarily polypropylene, nylon and PET, and also into thermosets for cross-linking.
Hybrid Plastics specializes in incorporating and upgrading ``vanilla'' resins that an end-user purchases from a resin producer, Lichtenhan said. ``Our customers want their existing resin to do more.''
Hybrid Plastics is finding market acceptance for POSS-infused methacrylics, epoxies and olefins, Lichtenhan said. ``The current applications are primarily focused in electronics and membranes.''
Interest in the possible uses of polymeric nanocomposites and polymer-layered silicate nanocomposites has waxed and waned two or three times in recent decades.
The current wave in the United States started about two years ago, said Joseph Koo, research engineer with the Texas Engineering Experiment Station in College Station, Texas. Available materials include specialized nylon 6 nanocomposites.
``Nylon and polypropylene are the first beneficiaries of this exciting new technology,'' said Peter Bins, president of global market research firm Bins & Associates in Sheboygan, Wis.
Recent developments with PP ``are particularly important because they demonstrate the viability of this nanotechnology in one of the most technically challenging base resins,'' Bins said. ``The opportunity to increase the stiffness of PP without significant deterioration in impact strength will broaden the market utility of this resin.''
Among material suppliers, RTP Co. of Winona, Minn., sells nanoclay in nylon and is beginning to sample PP- and polyethylene-based nanoclay compounds, said Sam Dahman, an RTP engineer.
Quietly, most major polymer producers pursue research and monitor opportunities, but generally have yet to see sufficient commercial demand to warrant the big bucks. Firms lost money when earlier bubbly expectations about nanomaterials imploded.
Karl Kamena remains enthusiastic about polymer nanocomposites, ``but we have yet to see the step-change improvements promised in host polymer properties,'' he said.
``The key drivers for large-scale commercial successes will be improvements in fundamental technologies and active involvement of the polymer producers,'' said Kamena, business development director with consulting firm Omni Tech International Ltd. in Midland, Mich. ``There is a tremendous amount of interest in the concept as measured by the many research projects in academic and government-supported labs, but there are few polymer producers who have committed major resources to the development of nanocomposites.''
Existing polymer technologies and products are a barrier to nanocomposite success.
``The business of companies is business, not the development of boutique technologies,'' Kamena said. ``A nanocomposite product may have a unique set of properties and performance, but for any given application it will probably not be uniquely suitable.
``A commercially successful nanocomposite product must beat competitive offerings,'' Kamena said.
In a current application, General Motors Corp. and partners Basell Polyolefins of Wilmington, Del., Southern Clay Products Inc. of Gonzales, Texas, and Blackhawk Automotive Plastics Inc. of Salem, Ohio, use thermoplastic olefin-layered silicate nanocomposites for an optional step-assist for 2002 GMC Safari and Chevrolet Astro vans that GM assembles in Baltimore.
For future applications, research scientists at a Zurich, Switzerland, laboratory of IBM Corp. achieved data storage density of one terabit per square inch using 10-nanometer-diameter tips to punch indentations in thin plastic film. Disclosed in June, the rate is about 20 times that of today's most dense electromagnetic storage systems. The initial target market: mobile telecommunication devices such as cellular telephones.
Huge potential for polymer nanostructured materials exists across the military scene, from aerospace to the U.S. Army foot soldier, said Richard Vaia.
Polymer nanocomposites will usher in a new era in materials development ``as surely as polymer composites changed the face of industry 25 years ago,'' said Vaia, senior materials scientist with the U.S. Air Force Research Laboratory near Dayton, Ohio. It's ``a difficult challenge to say where the real payoff is.''
While the Air Force wants high-end, high-performance materials, ``the Army wants what industry is interested in: low-cost volume'' materials, Vaia said. ``Polymer composites have been a mainstay of high-performance aircraft for over a quarter century. With the advent and application of nanotechnology, polymer composites could become even more attractive.''
The military aerospace community is interested in creating plastics with properties and performance beyond those available through conventional compounding and blending techno- logies. ``We are focused on examining numerous nanofillers including clay,'' Vaia said. Polymeric nanocomposites ``may provide enhanced, multifunctional matrix resins but should not be construed as a potential replacement for current, state-of-the-art carbon-fiber-reinforced composites.''
Vaia said the technology provides a route around traditional resin limitations.
The value of polymeric nanocomposites ``comes from providing value-added properties not present in the neat resin, without sacrificing its inherent processibility and mechanical properties,'' he said. ``Traditionally, blend or composite attempts at multifunctional materials require a trade-off between desired performance, mechanical properties, cost and processability.''
The Air Force is examining polymer-layered silicate nanocomposites for next-generation fiber-reinforced polymeric composites for use in unmanned aerial vehicles.
Other investigations look at the material's use in anti-flammability additives for aircraft interiors, gas-vapor barriers for packaging military food and beverage rations and barrier liners for cryogenic fuels in aerospace systems. Some experiments are done aboard the International Space Station.
Production of thermoplastic olefins ``will have huge payoffs,'' but, at the other extreme, modification of cyanate esters and bismaleimides ``is a much more challenging problem, Vaia said.
Defense procurement policies create a blockage.
``As long as we can identify applications with commercial partners, we have to buy from them,'' Vaia said. ``In today's environment, if it is not a $500 million industry, [major resin producers] are not going to talk to you about it.''