Nanotechnology coming of age: Between new and legacy industries, time for tiny tech is now

When famed physicist Richard Feynman posited in 1959 at the annual meeting of the American Physical Society, "Why can't we write the entire 24 volumes of the Encyclopedia Britannica on the head of a pin?" he was envisioning what would become nanotechnology.

At the time, Feynman offered $1,000 to the first person who could reduce the page of a book to 1/25,000 linear scale, essentially readable only by an electron microscope.

Feynman finally was forced to pay up a quarter-century later by a graduate student at Stanford University, Thomas H. Newman, who shrunk the first page of Charles Dickens' "A Tale of Two Cities." But it wasn't until 1991 when the theory of nanotechnology was propelled into existence by Japanese researcher Sumi Iijima, working with NEC Corp., with the discovery of the nanotube—a carbon-based filler that offers exceptional performance improvements in electrical conductivity, strength and other characteristics.

While some in the nanotechnology field believe carbon nanotubes—essentially graphene, nano-scale tubes of single-atom layer thickness or multiple layers wrapped to form a hollow core, comprised of carbon—may someday stand alone as the optimal performance additive in both tire and non-tire elastomers, others see a hybrid of CNT and carbon black as the filler of the future.

August Krupp, director of rubber development at Austin, Texas-based Molecular Rebar Design L.L.C., said CNTs "are another ingredient in the cupboard, allowing formulators and compounders to expand the magic triangle of performance properties."

The appropriately named Molecular Rebar Design, formed in 2009, supplies CNTs to manufacturers of rubber goods and tires, and represents one of the leading companies attempting to commercialize CNTs for this application space.

"Carbon nanotubes in general should be viewed as the next reinforcing filler of choice for many applications," Krupp said. "They can be used to replace carbon black and maybe silica in tires; they can be used as an electrically conductive and reinforcing filler in lead-acid and lithium-ion batteries; and they can work alongside typical fillers like carbon black and graphite."

Hybrid approach
It is this hybrid approach that interests both Mumbai, India-based Aditya Birla Group, a world leader in carbon black manufacturing, and Canton, Mass.-based Chasm Advanced Materials Inc., a smaller chemical manufacturer that focuses on opportunities in new materials and is more comfortable undertaking high-risk ventures, according to Aditya Birla's Zachary Combs.

"Chasm brings a strong entrepreneurial approach to established industries like ours," said Combs, who serves as Birla Carbon's manager for Materials Innovation Technology. "Birla Carbon's work with Chasm has resulted in the development of carbon black-CNT hybrid materials."

The nature of Birla Carbon's partnership with Chasm, much like Molecular Rebar's distribution partnership with Lyndhurst, N.J.-based Swan Chemical Inc. or Belgium-based Nanocyl's partnership with Uniontown, Ohio-based ChemSpec, is primarily a joint development agreement—although the Birla-Chasm partnership has evolved into an investment.

"Nanotechnology has the potential to extend tire and mechanical rubber goods performance beyond that which is achievable with existing fillers," Combs said. "This will primarily be achieved through a synergistic combination with carbon black and other fillers."

Krupp said the landscape of raw material suppliers in the rubber industry is changing.

"These still small but growing innovative companies are causing disruption in the mature rubber industry and are riding the wave of innovation, catalyzed by the growing adoption and technical requirements of EVs," he said. "We believe that nanotubes in particular will supplant carbon black as the reinforcing filler of choice in the future—a big statement, I know."

Paul Ferguson, director of business development with Chasm, disagrees in the potential wholesale replacement of the legacy filler.

"New materials are being discovered every day, with more than five elements being added to the periodic table since the arrival of the new millennium," he said. "If you consider that changes at the molecular level can result in remarkable outcomes, nanotechnology will continue to push the envelope of what's possible with existing and future materials. The pervasiveness of availability and maturity of manufacturing processes leveraging materials such as carbon black make it commercially unlikely that it will be replaced.

"However, the improvements that we've seen to date on CNT hybrids of carbon black indicate the future for new advanced materials is quite bright."

Better performance and a ways to go
Both Combs and Ferguson believe that CNTs have the potential to extend the performance of carbon black in tires and non-tire mechanical rubber goods. The unique attributes of CNTs can address gaps and deficiencies when used in combination with carbon black, Combs said, as CNTs have the potential to improve cut and chip, tear and conductivity in next-generation tires and MRGs.

And it is this performance triangle for tires—the "magic triangle" as Krupp calls it—that all additives (carbon black, silica-silane or CNTs, in combination or by themselves) are intended to benefit. Traditionally, there has been an inverse relationship between the points of that triangle: wear (or abrasion) resistance, rolling resistance (fuel economy and related CO2 emissions) and traction. As one is improved, another normally decreases in performance.

While both are forms of carbon, CNTs and carbon black have complementary properties that, when taken together, can produce measurable improvements in the entire triangle, Ferguson said.

"Improvements in one of these areas typically conflict with the others," he said. "For example, introducing an additive that makes a tire harder can improve tire life but will at the same time also reduce traction. Hybridizing the material at nanoscale has the potential to change this traditional dynamic beyond that which is achievable with simple fillers alone.

"And unlike a simple mixing of CNTs as a separate additive, the CNT hybrid is already integral on the carbon black particles to provide homogeneous dispersions so material properties are uniform and non-directionally dependent. CNT hybrids also offer an economy of material as the concentration can be precisely controlled and in a way that doesn't change the tire manufacturer's process."

Ferguson further touted the virtues of the CNT-carbon black hybrid additive, while noting that CNTs have excellent standalone properties in other applications.

"CNTs are the world's strongest material, they are flexible, form long chains and self-assemble into networks," he said. "However, the CNTs self-assembling nature can lead to problems with agglomeration when added as a simple dispersion. CNT hybrids overcome this and other limitations of the base material alone."

Krupp noted that "discrete and individualized" nanotubes provide "immense benefits" in small loadings.

"They are more reinforcing than carbon black, have fantastic electrical and thermal conductivity and can be used as a reinforcing filler in many applications," he said. "Essentially, this allows for a greater freedom in compound design. As filler-filler interactions mostly comprise Payne Effect, or hysteretic effects, using less filler in a high-performance application lowers dynamic properties—like rolling resistance."

According to Krupp, this means it's possible to design a compound with both improved abrasion resistance and improved rolling resistance (fuel economy) using solely CNTs. Conversely, a compound engineer could keep rolling resistance the same but make an extra tough compound, perhaps helping to design tires for the increased air pressure requirements of heavier electrical vehicles, for instance.

"The rod-like structure and high surface area of these nanotubes help to achieve the performance properties over typical spherical carbon black structures," he said. "The key here is dispersion, or the individual nanotubes being homogeneously located throughout the tire compound. If the nanotubes remain in a bundled state, they are just expensive, hairy, large particles like carbon black."

CNTs can be used to produce static-dissipative thermoplastic components with similar physical properties as the originals, Krupp said. Outside of the tire and non-tire elastomer world they have application, and similar performance achievements, in wear-resistant mill liners and conveyor belts, with improved cyclical fatigue, tear resistance and a better balance of properties for highly designed systems.

Combs added that for CNT hybrids, Birla has been approached by customers in the automotive, aerospace, electrical, conductive inks, medical device, and oil and gas industries, among many others.

Krupp added that producing nanotubes commercially (by the ton) has been a challenge since they have a significant amount of catalytic residue (namely heavy metals) and are produced in "clumps" or entangled structures of millions of tubes.

"Nanotubes produced commercially have drastically different properties than those tested in academia—namely that those bundles do not provide meaningful benefits versus their cost," he said. "These can be somewhat useful for electrically conductive applications, like static-dissipative plastics and batteries, but fail to bring good physical properties to applications like rubber parts or tires.

"MRD itself commercially sells our Molecular Rebar into lead-acid and lithium-ion batteries through our subsidiary, Black Diamond Structures. We also have sales in elastomer applications, for things like blow-out preventers in the oilfield, wear-resistant liners for mining applications, and off-the-road tire applications, like agricultural tractors."

Ferguson agreed that CNTs have evaded mass commercial penetration—"until now" with the Birla-Chasm hybrid technology—due to challenges with their functionalization.

"Hailed as a 'wonder material' due to its remarkable mechanical, electrical and optical physical properties and suitability in a broad range of applications, including electronics, engineering, medicine, biological, aerospace, defense and others, the breakthrough research completed between Birla and Chasm has produced novel methods overcoming those traditional challenges," Ferguson said.

Transforming industries old and new
Krupp said smaller, technical companies like Molecular Rebar Design and Chasm (through its partnership with the established Aditya Birla) are "causing disruption" within the mature rubber industry.

"What I think is sort of hidden behind the veil of supplier evaluations and research and development projects is that if you look at much of the rubber industry—whether tire manufacturers, rubber manufacturers, carbon black suppliers or others—you'll find that these players are more than 100 years old in many cases," he said.

To wit, Michelin was founded in 1889, while Orion Carbon Black (previously Degussa) has been making carbon black since 1862.

"It's incredible how long this industry has been around," Krupp said. "Big strides in innovation, in my opinion, are very difficult when the industry is so mature, but when they happen, it is ground breaking. When Evonik brought together silica-silane as the next-generation reinforcing filler, it changed the game. We believe carbon nanotubes can do the same thing.

"But we aren't a known player, we are a flea on a very large dog's back. This is a challenge, so we are having to get creative to cause disruption in our own way and break into this market."

Combs said companies like Chasm are most impactful by focusing on niche applications and enabling rapidly maturing technology.

"The true disruption is not just related to technologies, it is in finding disruptive ways of working together," Combs said. "We have seen the benefits of a large player like Birla Carbon working with an innovative start-up like Chasm. Partners like Chasm discover new disruptive technologies and mature companies like Birla Carbon have the ability to bring these developments to world-scale."

Ferguson echoed the virtues of such a partnership, in that Birla's "wealth of market knowledge" and "deep history" can accelerate the maturation of new technology.

"Chasm's expertise in advanced materials cuts across industries and applications providing increased opportunities for those serendipity or 'a ha' moments where new technological advancements offer promise in previously unconsidered applications," he said.

Without question, one of those applications is the EV revolution, where nanotechnology will be a major consideration for OEMs and aftermarket suppliers—whether that additive comes in hybrid or standalone fashion.

Since around 2015, CNT supply and demand has been growing quietly in the background, Krupp said.

"And this is at a greater scale and in more applications than one would assume," he said, adding that current figures suggest that worldwide supply capacity of multi-wall carbon nanotubes is greater than 3,000 tons per year, with demand for 2020 at more than 2,000 tons.

And more than 60 percent of these nanotubes were used in polymers—for electrical, thermal and mechanical strength purposes, exactly the applications that will be crucial in the EV industry.

"Reducing the weight of a rubber compound, while simultaneously improving both compound rolling resistance, heat buildup and wear resistance allows for greater freedom in other tire design aspects—new tread designs and overall thinner treads," he said. "Light-weighting tires is a big deal, and should have material impacts on the battery range of electrical vehicles."

And the unique properties of CNTs, Combs said, make them ideal candidates for applications requiring high levels of conductivity. This includes lithium-ion batteries, where performance demands such as faster charge and discharge, longer cycle life and higher energy density all can be impacted by the conductive additive.

"EVs present new challenges and opportunities for nanotechnology to address," Combs said. "Nanotechnology has the potential to enable improved performance in batteries, tires, conductive plastics and coatings and optoelectronic systems—all of which are pertinent to EVs. Nanotechnology will push the performance of existing fillers used in EV parts with respect to conductivity, electrostatic dissipation and light weighting."

At some point, all technologies reach an inherent limitation imposed by the platform itself. For EVs, that limitation is the driving range. Since EVs can't be quickly "refueled" like gasoline vehicles, consumers will be reluctant to invest in an EV if they're worried about being stranded under their normal commuting distances—and this acceptable distance is different for each consumer.

"EV manufacturers are motivated to continually increase the vehicle's range and charging characteristics in order to increase the vehicle's market appeal," Ferguson said. "Nanotechnology such as CNT hybrids has the potential to enable improved performance in batteries helping them to charge faster and last longer, reduce aerodynamic drag and the overall electrical draw on the vehicle."

With respect to sustainability and the related regulations and thresholds being established in virtually every first-world country today, nanotubes are more compatible with tire recycling and reuse processes, as compared to non-carbon fillers such as silica-silane.

"Applicable in conventional vehicles as well, CNT hybrids can overcome limitations in existing fillers used in a variety of automotive parts, making them stronger and lighter for increased fuel economy as well as economy of materials, putting less burden on increasingly scarce natural resources."

As Feynman envisioned more than 60 years ago, bigger will not, in fact, be better. And further innovation from the brightest minds in the industry will be a necessary evolution.

"Nanotechnology will be a big boon for society," Krupp said. "Obviously rubber is a big part of that— a huge market, with lots of applications ripe for innovation. Aside from rubber, there are so many untapped markets well-suited for nanotube adoption. At MRD, we have a lot of concrete ideas with baseline or proof-of-theory data, but can only focus on so many opportunities at a time."