Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Thermal Superconductivity in Carbon Nanotubes Not So “Super” When Added to Certain Materials

12.11.2003


Superb conductors of heat and infinitesimal in size, carbon nanotubes might be used to prevent overheating in next-generation computing devices or as fillers to enhance thermal conductivity of insulating materials, such as durable plastics or engine oil. But a research team at Rensselaer Polytechnic Institute has discovered that the nanotubes’ role as thermal superconductors is greatly diminished when mixed with materials such as polymers that make up plastics.



“Carbon nanotubes are superior thermal conductors by themselves. But, that doesn’t mean they will exhibit the same level of high conductivity when integrated into other materials,” says Pawel Keblinski, assistant professor of materials science and engineering and head of Rensselaer’s research team. His team’s research is published in this month’s issue of Nature Materials.

A global team of researchers was optimistic when a one-percent fraction of carbon nanotubes was added to epoxy and other organic materials, and the thermal conductivity of the newly created composites increased two- or threefold. But, using conventional engineering estimates, Keblinski noted that the composites’ conductivity should have had 50-fold increases.


Why such disparity between the experiment and the expectations?

“Atoms forming stiff carbon nanotubes vibrate at much higher frequencies than the atoms in the surrounding material. This leads to high interfacial resistance for the heat flow between the tubes and the other elements,” Keblinski says.

Energy exchange between two different elements is immediate and plentiful when frequencies in both are similar. Interfacial resistance happens when the frequencies are different, and the heat energy has a difficult time taking the leap from one element to the next.

To test the magnitude of the problem, Keblinski and his Rensselaer collaborators performed computer simulations on a model nanotube composite. Meanwhile, another research group headed by David Cahill at the University at Illinois at Urbana Champaign, heated real carbon nanotubes with a laser.

From the rate of cooling, in both the simulation and the physical experiment, the researchers derived the value of the interfacial resistance. In both instances, they found the resistance is so high that it limits the thermal conductivity of the nanotubes.

One way to reduce the interfacial resistance in such nanocomposites is to induce a stronger bond between the nanotube and other materials to make it easier for heat to cross from one element to the next. However, extensive bonding may distort the original nanotube structure that allows the tubes to be a superconductor of heat in the first place.

Still, Keblinski is optimistic about the use of carbon nanotubes to improve insulating materials. “By adding a small fraction of carbon nanotubes to such materials, we can still increase the thermal as well as electrical conductivity. So, although we may have to lower our expectations, we have not given up hope quite yet that nanotubes will improve materials for a number of applications,” Keblinski says.


About Rensselaer

Rensselaer Polytechnic Institute, founded in 1824, is the nation’s oldest technological university. The school offers degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of research centers that are characterized by strong industry partnerships. The Institute is especially well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

Jodi Ackerman | Rensselaer News

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>