Carbon nanotubes and graphene - properties, applications and market - Page 5

Researchers at Rice University have created a thin coating of graphene nanoribbons in epoxy, that has proven effective at melting ice on a helicopter blade. This coating may be an effective real-time de-icing mechanism for aircraft, wind turbines, transmission lines and other surfaces exposed to cold weather. In addition, the coating may also help protect aircraft from lightning strikes and provide an extra layer of electromagnetic shielding.

The scientists performed tests in which they melted centimeter-thick ice from a static helicopter rotor blade in a -4 degree Fahrenheit environment. When a small voltage was applied, the coating delivered electrothermal heat - called Joule heating - to the surface, which melted the ice.

Researchers have reported a graphene-based material with special electric properties, which might enable the production of better energy storage devices. The material follows the predictions of physicists from the University of Luxembourg that three years ago had theoretically predicted the unusual characteristics of a particular composite material. These calculations could now finally be confirmed by experiment in cooperation with the Centre de Recherche Paul Pascal in Bordeaux, France, and resulted in the discovery of a so-called high-k-material, which might enable the production of better energy storage devices the basis for smaller, faster and more efficient electronics.

Earlier calculations indicated disappointing results - certain compound materials made of polymers and flaky graphene, as opposed to those made of polymers and carbon nanotubes, did not increase the conductivity of the material to the degree that was generally expected until then. These were bad news that clouded graphene's perceived future in creating composites with increased conductivity. 

IBM scientists announced a remarkable engineering achievement - they have managed to exchange the silicon transistor contacts in transistors for smaller, more efficient, carbon nanotubes. This could have revolutionary potential as silicon is getting harder to shrink in size, while CNTs can allow a reduction in the size of transistors.

The smaller silicon transistor contacts get, the higher their electrical resistance becomes. There comes a point where the components simply get too small to conduct electrons efficiently and it seems that silicon is nearing that point. Carbon nanotubes, on the other hand, are a different story. They measure less than 10 nanometers in diameter (less than half the size of today's smallest silicon transistor contact) and IBM actually had to devise a new means of attaching these tiny components. Known as an "end-bonded contact scheme" the 10 nm electrical leads are chemically bonded to the metal substructure. Replacing these contacts with carbon nanotubes won't just allow for computers to crunch more data, faster. This breakthrough ensures that they'll continue to shrink, following Moore's Law, for several iterations beyond what silicon components are capable of.

In a research funded by a U.S. Department of Defense-Multidisciplinary University Research Initiative grant and Wenzhou Medical University, an international team of scientists has developed what is referred to as the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in 3D. The research may hold potential for increased energy storage in high efficiency batteries and supercapacitors, increasing the efficiency of energy conversion in solar cells, for lightweight thermal coatings and more. 

The group's early testing showed that a 3D fiber-like supercapacitor made with uninterrupted fibers of carbon nanotubes and graphene matched or even surpassed bettered the reported record-high capacities for such devices. When tested as a counter electrode in a dye-sensitized solar cell, the material enabled the cell to convert power with up to 6.8% efficiency and more than doubled the performance of a similar cell that used an expensive platinum wire counter electrode. 

A few weeks ago we reported on a new IDTechEx market report, in which they predict that the graphene market will reach nearly $200 million by 2026, with the estimation that the largest sectors will be composites, energy applications and graphene coatings.

We were very interested in learning more, and Dr Khasha Ghaffarzadeh, IDTechEx's head of consulting was kind enough to answer a few questions and explain the company's view on the graphene market.

Q: IDTechEx has been following graphene for a long time with dedicated events and reports. Why is this new material interesting for IDTechEx?

We have a long track record of analyzing emerging advanced materials such as quantum dots, CNTs, Ag nanostructures, silicon nanostructures, OLED materials, etc. We were however pulled into the world of graphene by our clients’ questions. Once in, we soon realized that there is a big synergy between graphene and our events. in fact, our events on supercapacitors and printed electronics were the right near-term addressable market for graphene, and that is why we managed to rapidly build up the largest business-focused event on graphene. Our events on graphene are held in the USA and Europe each year see www.IDTechEx.com/usa.

A collaboration between researchers from Cardiff University and Haydale conducted a study focused on component-scale hierarchical composites using nanocarbons, mainly graphene and CNTs. The team's main aim was to explore techniques for component-scale manufacture of hierarchical composites by liquid infusion.

A plasma process, developed by Haydale, was adopted for controllable functionalization of large batches of nanocarbons (100s of grams) prior to mixing with epoxy resin. A rheological study indicated that filler morphology, functionalization and fill weight all have an effect on epoxy resin viscosity. Using these developed nanocomposite resins, a resin infusion under flexible tooling (RIFT) technique was developed. Resin flow studies informed an optimum setup that facilitated full wet-out of large area UD carbon fibre laminates and the resulting materials showed significant improvements in mechanical properties, demonstrating up to ~50% increase in compression after impact (CAI) properties.

A research team at the University of Michigan utilized Japanese paper cutting techniques, called kirigami, to create a new type of flexible conductor. The team believes that this technique may open up big possibilities for implantable medical devices, which have to flex and bend within the human body to work. Another option is gadgets that won't break when bending or flexing.

The first prototype of the kirigami stretchable conductor consisted of tracing paper covered in carbon nanotubes. The layout was quite simple, with cuts like rows of dashes. Later concepts were more intricate. for example, conductor sheets made out of graphene oxide, with etching cuts into the surface just a tenth of a millimeter long using laser beams and a plasma of oxygen ions and electrons.

Researchers at Rice University, the Indian Institute of Technology and the Lebanese American University discovered that grinding carbon nanotubes might be a simple way of forming graphene nanoribbons. The research indicates that a simple process like grinding could deliver strong chemical coupling between solid nanostructures and produce novel forms of products with specific properties.

The scientists mixed two types of chemically modified nanotubes (one with carboxyl groups and the other with hydroxyl groups attached) and ground them together for about 20 minutes using a mortar and pestle. They noticed that when the two types of nanotubes come into contact during grinding, they react and unzip, a process that until now has depended largely on reactions in specific chemical solutions.

Malaysian-based Felda Global Ventures Holdings (FGV) aims to set up a graphene plant in the country within two years and become the largest graphene materials producer in Asia.

FGV Executive Vice-President of the Palm Downstream Cluster said that the RM15 million (around 4,080,000 USD) plant is expected to have a production capacity of 9 kilogramme of graphene per day. The location of the plant is unspecified, but is expected to be located at one of FGV's mills.

Scientists from the Novosibirsk Nikolayev Inorganic Chemistry Institute and the Krasnoyarsk Biophysics Institute have invented a new composite material made of graphene and nano-diamonds. By placing nano-diamonds on the surface of vertically aligned tubes of graphene (probably carbon nanotubes), the scientists created a unique composite material that glows under the impact of a weak electric field.

The researchers say this is the prototype of a tiny light fixture, a nano-tube with a glowing nano-diamond on top. Such structures can be used in a variety of fields, from new types of displays to health diagnostics techniques.