Featured Research

from universities, journals, and other organizations

Thermal Superconductivity In Carbon Nanotubes Not So 'Super' When Added To Certain Materials

Date:
November 12, 2003
Source:
Rensselaer Polytechnic Institute
Summary:
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.

TROY, N.Y.-- 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.


Story Source:

The above story is based on materials provided by Rensselaer Polytechnic Institute. Note: Materials may be edited for content and length.


Cite This Page:

Rensselaer Polytechnic Institute. "Thermal Superconductivity In Carbon Nanotubes Not So 'Super' When Added To Certain Materials." ScienceDaily. ScienceDaily, 12 November 2003. <www.sciencedaily.com/releases/2003/11/031112072719.htm>.
Rensselaer Polytechnic Institute. (2003, November 12). Thermal Superconductivity In Carbon Nanotubes Not So 'Super' When Added To Certain Materials. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2003/11/031112072719.htm
Rensselaer Polytechnic Institute. "Thermal Superconductivity In Carbon Nanotubes Not So 'Super' When Added To Certain Materials." ScienceDaily. www.sciencedaily.com/releases/2003/11/031112072719.htm (accessed July 23, 2014).

Share This




More Matter & Energy News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com
9/11 Commission Members Warn of Terror "fatigue" Among American Public

9/11 Commission Members Warn of Terror "fatigue" Among American Public

Reuters - US Online Video (July 22, 2014) Ten years after releasing its initial report, members of the 9/11 Commission warn of the "waning sense of urgency" in combating terrorists attacks. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins