February 28, 2011 — Various industries — such as aerospace, sporting goods manufacturers, construction – are incorporating technological advances using nanocomposites, with extraordinary results. Epoxy materials are being transformed into stiffer, lighter, and stronger materials thanks to the addition of fullerenes and carbon nanotubes (CNTs). Dongsheng Mao, Applied Nanotech, Applied Nanotech Holdings (APNT), describes a process involving multi-walled carbon nanotubes (MWCNTs) that have stronger mechanical properties yet remain lightweight and within end-product cost parameters.

These epoxy materials frequently appear in industry as fiber reinforced plastics (FRP). The properties of these new epoxy/carbon nanotube composites are generally not easily transferred to the FRP. However, using this new composite, APNT achieved a 31% improvement in the flexural strength of the final FRP and similar improvements are expected in compression strength.

Figure 1. Schematic diagram of carbon nanotube (CNT) reinforced epoxy. Strong bonding between functionalized carbon nanotubes and epoxy is formed to significantly improve mechanical properties of the composites.

The epoxy/CNT nanocomposite material has properties tailored to 3D assembling, thanks to an ability to uniquely handle blocks of CNTs. Large-volume applications include golf club shaft and sports racquet manufacture. Manufacturers using this material can decrease product weight while maintaining strength, portability, and flexibility. Sporting goods products are only the first application area.

The role carbon nanotubes play

Only 1-2% of the product is carbon nanotubes, yet they improve mechanical properties. By dispersing and functionalizing CNTs individually, ANI spread the CNTs throughout an epoxy matrix such that, when force is applied on the final product, a part of that stress is transferred to the CNTs.

CNTs possess unique mechanical properties. Their stiffness, strength and resilience exceed similar properties of any current material, with the potential for fundamentally new material systems, in particular, structural nanocomposites. Unfortunately, their integration with polymer matrices presents new technical challenges.

CNTs tend to aggregate with each other to form ropes or bundles due to intrinsic van der Waals forces associated with their high surface energy. De-agglomeration and dispersion of CNTs in various media has been recognized as one of the major challenges of commercial CNT adoption. Traditional methods such as sonication, high-shear mixing, stirring, and surfactants are often used in lab-scale quantities to disperse CNTs, but those methods have proven ineffective on an industrial scale. Although surface functionalization of CNTs has improved dispersions, the results for the mechanical properties of CNT-reinforced nanocomposites also depend on mixing procedures and carbon fiber-reinforced polymer (CFRP) manufacture methods.

Transferring interesting and unique nanocomposite properties to CFRPs can be realized only by successfully integrating functionalized CNTs into more complex structures. Using CNTs as a reinforcing component in polymer composites requires the ability to tailor the nature of the CNT walls to control the interfacial interactions between the CNTs and the polymer chains.

Applied’s CNT achieved over 40% improvement in both flexural and compression strength for epoxy/carbon nanotube composites. Chemical and mechanical modification and CNT functionalization, for them to be accepted and integrated properly into the epoxy matrix, were essential.

Figure 2. Yonex’s new golf clubs (EZONE) are made using Applied Nanotech, Inc’s patented technology (www.yonex.co.jp).

Commercializing new CNT products

At times, companies worry about sharing propriety research information. Without all of the pertinent data, it is difficult to clearly understand how to apply nanotechnology methods to achieve the desired result. In cases like this, if the CNTs are not functionalized properly, or epoxy penetration into the fiber is suboptimal, the final material will have visible defects and no mechanical enhancement. Communication between industry and research entities is therefore essential to develop commercially viable products, as APNT demonstrates with this sporting goods partner.

Cost is always a manufacturing consideration. Even the greatest design improvements fail in the market if consumer cost is prohibitive. We advise clients to carefully examine how nanotechnology is applied to a project. In the past, single-wall nanotubes (SWCNTs) have enabled some great results, but costs were exorbitant. Today, functionalized CNT prices are dropping considerably, so we focused on MWCNTs. The results were significantly improved compression strength, flexural strength, modulus, impact strength, and vibration damping factor compared with epoxy.

We have demonstrated that the functionalization and dispersion methods used in CNT-reinforced epoxy and other thermosetting nanocomposites is a promising technology that can be expanded into many other fields, including aviation, defense, aerospace, marine, and cleantech.

Dongsheng Mao received his Ph.D from Chinese Academy of Sciences with a background of Materials Science and Engineering and is director of the Nanocomposite Division at Applied Nanotech. Inc., Applied Nanotech Holdings (Stock Symbol: APNT), 3006 Longhorn Blvd., Suite 107, Austin, TX 78758; [email protected]. Dongsheng Mao is director of Applied Nanotech Inc.’s Nanocomposite Division.

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February 25, 2011 – Global production value of nanocarbon products — single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), fullerenes, graphene, carbon nanofiber, and nanodiamonds — will triple over the next four years in value, and by orders-of-magnitude in actual production, according to a recent analyst report.

Production of carbon nano products totaled about 710 tons in 2010, for a rough value of $435M, calculates Innovative Research and Products Inc. (iRAP). The company predicts that will swell to 9,300t and $1.3B by 2015.

Nanocarbon production value (in US $M) according to types. (Source: iRAP)

Inside the numbers, iRap finds some key trends:

• Production closing the capacity gap. Those surging output numbers for nanocarbon products suggest partially solving a more important problem: massive overcapacity. In 2010, production capacity for these materials was 4065t — actual output of 710t translates to 17% capacity utilization. (Output was only about 500t in 2009, and 340t in 2008.) But by 2015, iRap sees this gulf closing, with actual production doubling over the period to exceed 9300t (a 67.3% annual growth rate), translating to an 80% utilization based on the 12,300t of projected capacity.

Despite surging output and capacity, demand hasn’t really caught up yet, iRap notes, but suppliers want to be ready to match future demand seen coming in the next 5-10 years. Contributing to that demand spark, overall prices are coming down: the firm projects prices for all nanocarbon products will fall by an average of ~12%/year from 2010-2015.

• Nanotubes leading the way. Multiwalled carbon nanotubes (MWNT) will pace the growth, says iRap: 390t of global capacity in 2008, 1500t in 2009, >3400t in 2010, and 9400t by 2015. But single-walled carbon nanotubes (SWNT), the most expensive of the lot, are the key to the kingdom; they "are much more difficult to produce than MWCNTs," iRap notes, and are seen replacing silicon as the ubiquitous electronic starting material within the next decade or so.
• Asia is production home. Asia’s production capacity for both types of nanotubes (SWNT and MWNT) is 2×-3× higher than North America and Europe combined, says iRap. Japan is a leader in MWNT production (driven by demand for lithium-ion battery electrodes) but China and Korea are catching up fast.


Share of nanocarbon production value according to types, 2015 vs. 2010. (Source: iRAP)

February 25, 2011 – Global production value of nanocarbon products — single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), fullerenes, graphene, carbon nanofiber, and nanodiamonds — will triple over the next four years in value, and by orders-of-magnitude in actual production, according to a recent analyst report.

Production of carbon nano products totaled about 710 tons in 2010, for a rough value of $435M, calculates Innovative Research and Products Inc. (iRAP). The company predicts that will swell to 9,300t and $1.3B by 2015.

Nanocarbon production value (in US $M) according to types. (Source: iRAP)

Inside the numbers, iRap finds some key trends:

• Production closing the capacity gap. Those surging output numbers for nanocarbon products suggest partially solving a more important problem: massive overcapacity. In 2010, production capacity for these materials was 4065t — actual output of 710t translates to 17% capacity utilization. (Output was only about 500t in 2009, and 340t in 2008.) But by 2015, iRap sees this gulf closing, with actual production doubling over the period to exceed 9300t (a 67.3% annual growth rate), translating to an 80% utilization based on the 12,300t of projected capacity.

Despite surging output and capacity, demand hasn’t really caught up yet, iRap notes, but suppliers want to be ready to match future demand seen coming in the next 5-10 years. Contributing to that demand spark, overall prices are coming down: the firm projects prices for all nanocarbon products will fall by an average of ~12%/year from 2010-2015.

• Nanotubes leading the way. Multiwalled carbon nanotubes (MWNT) will pace the growth, says iRap: 390t of global capacity in 2008, 1500t in 2009, >3400t in 2010, and 9400t by 2015. But single-walled carbon nanotubes (SWNT), the most expensive of the lot, are the key to the kingdom; they "are much more difficult to produce than MWCNTs," iRap notes, and are seen replacing silicon as the ubiquitous electronic starting material within the next decade or so.
• Asia is production home. Asia’s production capacity for both types of nanotubes (SWNT and MWNT) is 2×-3× higher than North America and Europe combined, says iRap. Japan is a leader in MWNT production (driven by demand for lithium-ion battery electrodes) but China and Korea are catching up fast.


Share of nanocarbon production value according to types, 2015 vs. 2010. (Source: iRAP)

February 24, 2011 — A lab at Rice University has developed an efficient method to disperse nanotubes in a way that preserves their unique properties and adds more. The technique allows inorganic metal complexes with different functionalities to remain in close contact with single-walled carbon nanotubes (SWCNT) while keeping them separated in a solution.

That separation is critical to manufacturers who want to spin fiber from nanotubes, or mix them into composite materials for strength or to take advantage of their electrical properties. The ability to functionalize the nanotubes at the same time may advance imaging sensors, catalysis and solar-activated hydrogen fuel cells.

A batch of nanotubes can stay dispersed in water for weeks on end. Keeping carbon nanotubes from clumping in aqueous solutions and combining them with molecules that add novel abilities have been difficult for scientists exploring the use of these highly versatile materials. They’ve tried attaching organic molecules to the nanotubes’ surfaces to add functionality as well as solubility. But while these techniques can separate nanotubes from one another, they take a toll on the nanotubes’ electronic, thermal and mechanical properties.

Angel Marti, a Rice assistant professor of chemistry and bioengineering and a Norman Hackerman-Welch Young Investigator, and his students reported this month in the Royal Society of Chemistry journal Chemical Communications that ruthenium polypyridyl complexes are highly effective at dispersing nanotubes in water efficiently and for long periods. Ruthenium is a rare metallic element.

Marti and his team created ruthenium complexes by combining the element with ligands, stable molecules that bind to metal ions. The resulting molecular complex is part hydrophobic (the ligands) and part hydrophilic (the ruthenium). The ligands strongly bind to nanotubes while the attached ruthenium molecules interact with water to maintain the tubes in solution and keep them apart from one another.

Another key turned out to be moderation. Marti and co-authors Disha Jain and Avishek Saha — Jain is a former postdoctoral researcher in Marti’s lab, and Saha is a graduate student — were originally eyeing ruthenium complexes as part of a study to track amyloid deposits associated with Alzheimer’s disease. "We started to wonder what would happen if we modified the metal complex so it could bind to a nanotube," Marti said. "That would provide solubility, individualization, dispersion and functionality."

"Avishek put this together with purified single-walled carbon nanotubes (created via Rice’s HiPco process) and sonicated. Absolutely nothing happened. The nanotubes didn’t get into solution — they just clumped at the bottom.

"That was very weird, but that’s how science works — some things you think are good ideas never work."

Saha removed the liquid and left the clumped nanotubes at the bottom of the centrifuge tube. "So I said, ‘Well, why don’t you do something crazy. Just add water to that, and with the little bit of ruthenium that might remain there, try to do the reaction.’ He did that, and the solution turned black."

A low concentration of ruthenium did the trick. "We found out that 0.05% of the ruthenium complex is the optimum concentration to dissolve nanotubes," Marti said. Further experimentation showed that simple ruthenium complexes alone did not work. The molecule requires its hydrophobic ligand tail, which seeks to minimize its exposure to water by binding with nanotubes. "That’s the same thing nanotubes want to do, so it’s a favorable relationship," he said.

Marti also found the nanotubes’ natural fluorescence unaffected by the ruthenium complexes. "Even though they’ve been purified, which can introduce defects, they still exhibit very good fluorescence," he said.

He said that certain ruthenium complexes have the ability to stay in an excited state for a long time — about 600 nanoseconds, or 100 times longer than normal organic molecules. "It means the probability that it will transfer an electron is high. That’s convenient for energy transfer applications, which are important for imaging," he said.

That nanotubes stay suspended for a long time should catch the eye of manufacturers who use them in bulk. "They should stay separated for weeks without problems," Marti said. "We have solutions that have been sitting for months without any signs of crashing."

The Welch Foundation supported the research.

More information can be found at www.rice.edu

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February 24, 2011 – FARS News Agency — Iranian researchers at Kashan University calculated the physical and mechanical properties of multi-walled carbon nanotubes (MWCNT) and nitride-Bohr nanotubes in a move to help improve the design of arms for nano-robots.

The body of the nano robot has joints or fixed points around which arms move. This research studies the various stability types of two-walled or multi-walled carbon nanotubes in an elastic environment around these moving parts. "What distinguishes this study from all other researches carried out recently is the presentation of Pasternak model that considers the effect of shear forces applied by the elastic environment to the two-walled carbon nanotubes," Dr. Ali Qorbanpour Arani, a lecturer at University of Kashan, told the Iran Nanotechnology Initiative Council.

Arani, a member of the Nanoscience and Nanotechnology Research Center of University of Kashan added, "In this study, the physical and mechanical properties of the multi-walled carbon and nitride-Bohr nanotubes were determined. The properties can be used in the design of nano-robots’ arms. In addition, they can be used as intelligent nanotubes due to their piezoelectric properties by using electrical field on them, and they can control the rotation and movement or the kinetic of the movement in the arms and neck of the nano-robot."

"Taking into account the fact that nanotubes are usually studied in an elastic environment, in order to calculate the forces applied to nanotubes, which include vertical and shear forces, we used Winkler model (for studying the vertical forces) and Pasternak model (for the vertical and shear forces) to obtain more precise results," Qorbanpour Arani concluded.

Copyright 2011 Fars News Agency. All Rights Reserved

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