Featured Research

from universities, journals, and other organizations

Shear Ingenuity: Tweaking The Conductivity Of Nanotube Composites

Date:
February 14, 2008
Source:
National Institute of Standards and Technology
Summary:
One of the immediate applications of carbon nanotubes (CNT) is as an additive to polymers to create electrically conducting plastics--a relatively low CNT concentration can dramatically change the polymer's electrical conductivity by orders of magnitude, from an insulator to a conductor. New measurements have uncovered an intriguing wrinkle. For a given CNT concentration, the electrical properties of the composite can be tuned from being a conductor to a non-conductor simply by changing processing conditions -- basically how fast the polymer flows.

Confocal microscope image of a carbon nanotube/polypropylene composite. Small concentrations of carbon nanotubes--here about one percent by mass--can change the electrical properties of the polymer dramatically.
Credit: Image courtesy of National Institute of Standards and Technology

One of the immediate applications of carbon nanotubes (CNT) is as an additive to polymers to create electrically conducting plastics—a relatively low CNT concentration can dramatically change the polymer‘s electrical conductivity by orders of magnitude, from an insulator to a conductor.

New measurements by scientists at the National Institute of Standards and Technology (NIST) have uncovered an intriguing wrinkle. For a given CNT concentration, the electrical properties of the composite can be tuned from being a conductor to a non-conductor simply by changing processing conditions—basically how fast the polymer flows.

Carbon nanotubes—sheets of graphite rolled up into nanoscale hollow cylinders—are under intense scrutiny for a wide range of materials applications. The NIST study* shows how the conductivity and dielectric properties of these mixtures depend on flow and how they change once flow has stopped.

These property changes have relevance to the process design of these materials in a long list of potential applications for conducting plastics including transparent electrodes, antennas, electronic packaging, sensors, automotive paint, anti-static fuel hoses and aircraft components.

The NIST researchers augmented a standard instrument, a shear rheometer, normally used for viscosity measurements, to simultaneously measure conductivity and dielectric properties Using this “rheo-dielectric spectrometer,” they discovered that the conductivity of the nanocomposite dramatically decreases with increasing flow rate, effectively changing the material from a conductor to an insulator.

This extraordinary sensitivity of the conductivity (and other properties) to flow is prevalent near a characteristic CNT concentration where an interpenetrating CNT network first forms. Surprisingly, once the flow is removed, they found that the nanocomposite reverts back to its original conductivity.

Based on these measurements, the NIST team proposed a theoretical model that successfully accounts for these dramatic effects. This model quantitatively predicts the observed conductor-insulator transition and is useful for optimizing and controlling the properties of these new polymer-nanotube composites.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Cite This Page:

National Institute of Standards and Technology. "Shear Ingenuity: Tweaking The Conductivity Of Nanotube Composites." ScienceDaily. ScienceDaily, 14 February 2008. <www.sciencedaily.com/releases/2008/02/080208182237.htm>.
National Institute of Standards and Technology. (2008, February 14). Shear Ingenuity: Tweaking The Conductivity Of Nanotube Composites. ScienceDaily. Retrieved September 29, 2014 from www.sciencedaily.com/releases/2008/02/080208182237.htm
National Institute of Standards and Technology. "Shear Ingenuity: Tweaking The Conductivity Of Nanotube Composites." ScienceDaily. www.sciencedaily.com/releases/2008/02/080208182237.htm (accessed September 29, 2014).

Share This



More Matter & Energy News

Monday, September 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CERN Celebrates 60 Years of Science

CERN Celebrates 60 Years of Science

Reuters - Business Video Online (Sep. 29, 2014) CERN, the European Organisation for Nuclear Research, celebrates 60 years of bringing nations together through science. As Joanna Partridge reports from inside the famous science centre it's also planning to turn the Large Hadron Collider particle accelerator back on after an upgrade. Video provided by Reuters
Powered by NewsLook.com
This 'Invisibility Cloak' Is Simpler Than Most

This 'Invisibility Cloak' Is Simpler Than Most

Newsy (Sep. 28, 2014) Researchers from the University of Rochester have created a type of invisibility cloak with simple focal lenses. Video provided by Newsy
Powered by NewsLook.com
New Corvette Can Secretly Record Convos And Get You Arrested

New Corvette Can Secretly Record Convos And Get You Arrested

Newsy (Sep. 28, 2014) The 2015 Corvette features valet mode – which allows the owner to secretly record audio and video – but in many states that practice is illegal. Video provided by Newsy
Powered by NewsLook.com
Google Tightens Requirements For Android Manufacturers

Google Tightens Requirements For Android Manufacturers

Newsy (Sep. 27, 2014) Phonemakers who want to use Google’s software in their devices will have to stick to more stringent requirements. Video provided by Newsy
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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