Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > MIT scientists transform polyethylene into a heat-conducting material

The new method involves pulling a thin thread of material (top) from a liquid solution (bottom), and in the process the individual polymer filaments, which start out as a tangled mass, become very highly aligned.  Illustration courtesy of Gang Chen
The new method involves pulling a thin thread of material (top) from a liquid solution (bottom), and in the process the individual polymer filaments, which start out as a tangled mass, become very highly aligned. Illustration courtesy of Gang Chen

Abstract:
Conducts heat just as well as most metals, yet remains an electrical insulator

MIT scientists transform polyethylene into a heat-conducting material

Cambridge, MA | Posted on March 8th, 2010

Most polymers — materials made of long, chain-like molecules — are very good insulators for both heat and electricity. But an MIT team has found a way to transform the most widely used polymer, polyethylene, into a material that conducts heat just as well as most metals, yet remains an electrical insulator.

The new process causes the polymer to conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. This may make the new material especially useful for applications where it is important to draw heat away from an object, such as a computer processor chip. The work is described in a paper published on March 7 in Nature Nanotechnology.

The key to the transformation was getting all the polymer molecules to line up the same way, rather than forming a chaotic tangled mass, as they normally do. The team did that by slowly drawing a polyethylene fiber out of a solution, using the finely controllable cantilever of an atomic force microscope, which they also used to measure the properties of the resulting fiber.

This fiber was about 300 times more thermally conductive than normal polyethylene along the direction of the individual fibers, says the team's leader, Gang Chen, the Carl Richard Soderberg Professor of Power Engineering and director of MIT's Pappalardo Micro and Nano Engineering Laboratories.

The high thermal conductivity could make such fibers useful for dissipating heat in many applications where metals are now used, such as solar hot water collectors, heat exchangers and electronics.

Chen explains that most attempts to create polymers with improved thermal conductivity have focused on adding in other materials, such as carbon nanotubes, but these have achieved only modest increases in conductivity because the interfaces between the two kinds of material tend to add thermal resistance. "The interfaces actually scatter heat, so you don't get much improvement," Chen says. But using this new method, the conductivity was enhanced so much that it was actually better than that of about half of all pure metals, including iron and platinum.

Producing the new fibers, in which the polymer molecules are all aligned instead of jumbled, required a two-stage process, explains graduate student Sheng Shen, the lead author of the paper. The polymer is initially heated and drawn out, then heated again to stretch it further. "Once it solidifies at room temperature, you can't do any large deformation," Shen says, "so we heat it up twice."

Even greater gains are likely to be possible as the technique is improved, says Chen, noting that the results achieved so far already represent the highest thermal conductivity ever seen in any polymer material. Already, the degree of conductivity they produce, if such fibers could be made in quantity, could provide a cheaper alternative to metals used for heat transfer in many applications, especially ones where the directional characteristics would come in handy, such as heat-exchanger fins (like the coils on the back of a refrigerator or in an air conditioner), cell-phone casings or the plastic packaging for computer chips. Other applications might be devised that take advantage of the material's unusual combination of thermal conductivity with light weight, chemical stability and electrical insulation.

So far, the team has just produced individual fibers in a laboratory setting, Chen says, but "we're hoping that down the road, we can scale up to a macro scale," producing whole sheets of material with the same properties.

Ravi Prasher, an engineer at Intel, says that "the quality of the work from Prof. Chen's group has always been phenomenal," and adds that "this is a very significant finding" that could have many applications in electronics. The remaining question, he says, is "how scalable is the manufacturing of these fibers? How easy is it to integrate these fibers in real-world applications?"

This work, which also included Chen's former graduate students Asegun Henry and Jonathan Tong, was supported by the National Science Foundation and the Department of Energy's Office of Basic Energy Sciences.

Source: Shen S, Henry A, Tong J, Zheng R, Gang Chen G. Polyethylene nanofibres with very high thermal conductivities. Nature Materials. 7 March 2010.

####

About MIT
The mission of MIT is to advance knowledge and educate students in science, technology and other areas of scholarship that will best serve the nation and the world in the 21st century — whether the focus is cancer, energy, economics or literature.

For more information, please click here

Contacts:
Jen Hirsch
MIT News Office

T: 617-253-1682

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Possible Futures

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Academic/Education

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Haydale Announces Collaboration Agreement with Swansea University’s Welsh Centre for Printing and Coatings (WCPC) July 12th, 2014

STFC takes delivery of the 100th Hitachi Tabletop SEM in the UK July 3rd, 2014

Innovation Management and the Emergence of the Nanobiotechnology Industry July 1st, 2014

Chip Technology

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Nanometrics Reports Second Quarter 2014 Financial Results July 30th, 2014

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nanoelectronics

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

3-D nanostructure could benefit nanoelectronics, gas storage: Rice U. researchers predict functional advantages of 3-D boron nitride July 15th, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Announcements

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE