Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Computer model maps strengths, weaknesses of nanotubes

Abstract:
Materials scientists develop predictive tool for nanotube breaks

Computer model maps strengths, weaknesses of nanotubes

Houston, TX | Posted on March 27, 2006

In theory, carbon nanotubes are 100 times stronger than steel, but in practice, scientists have struggled make nanotubes that live up to those predictions, in part, because there are still many unanswered questions about how nanotubes break and under what conditions.

Because nanotubes are single molecules – about 80,000 times smaller than a human hair – finding out what makes them break involves the study of molecular bonds, atomic dynamics and complex quantum phenomena. The fact that there are hundreds of different kinds of nanotubes, sometimes with radically different properties, adds to the complexity.

A new computer modeling approach developed by materials scientists at Rice University and University of Minnesota is allowing researchers to create a "strength map" that plots the likelihood or probability that a nanotube will break – and how it's likely to break – based on four key variables.

"Nanotubes break in one of two ways: the bonds either snap in a brittle fashion or they stretch and deform," said Boris Yakobson, professor of mechanical engineering and materials science and of chemistry. "We found that the underlying mechanisms that cause both types of breaks are each present at the same time. Even in a particular test, either type of break can occur, but we were able to map out a pattern – based on statistical probabilities – of what was likely to occur in a range of conditions for the whole catalog of nanotube species."

Yakobson's results appear in this week¹s online edition of the Proceedings of the National Academy of Sciences.

Carbon nanotubes are single molecules of pure carbon. They are long, narrow, hollow cylinders with walls just one atom thick. Scientists estimate SWNTs are about 100 times stronger than steel at one-sixth the weight. By comparison, Kevlar® -- the fiber used in most bulletproof body armor -- is about five times stronger than an equal weight of steel.

The precise diameter of a nanotube can vary from less than half of a nanometer – a billionth of a meter – to more than three nanometers. Nanotubes can also vary by the angle at which they are twisted. This is known as the chiral angle, and a useful analogy is a roll of gift-wrap paper. If the roll is rewound carefully, there is no overhang on either end. However, if the roll wound at an odd angle, excess paper hangs off at one end.

The chiral angle of nanotubes can vary from 0 degrees (no paper hanging off the roll) to 30 degrees, and tubes with different chiralities and diameters can have very different physical properties. Some are metals for instance and others are not.

In developing his computational model of nanotube breaking patterns, Yakobson consider four critical values: load level, load duration, temperature and chirality.

"The breaking mechanism for a particular nanotube depends to a great extent on its intrinsic twist called chirality," said co-author Traian Dumitrica, a former Rice postdoctoral researcher who is now assistant professor of mechanical engineering at the University of Minnesota. "Yet, temperature still influences the outcome. We were able to summarize the intricate dependence on parameters in a map, which stands as a striking example for the predictive power of simulations in materials science research."

####


Rice doctoral student Ming Hua also co-authored the paper. The research was funded by NASA, the Office of Naval Research and the Welch Foundation.

About Rice University:
Rice University is consistently ranked one of America's best teaching and research universities. It is distinguished by its: size: 2,850 undergraduates and 1,950 graduate students; selectivity: 10 applicants for each place in the freshman class; resources: an undergraduate student-to-faculty ratio of 6-to-1, and the fifth largest endowment per student among American universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work. Rice's wooded campus is located in the nation's fourth largest city and on America's South Coast.

For more information, please click here

Contact:
Jade Boyd
(713) 348-6778
jadeboyd@rice.edu

Copyright © Rice University

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

Nanotubes/Buckyballs

University of Houston researchers create new method to draw molecules from live cells: Technique using magnetic nanomaterials offers promise for diagnosis, gene therapy July 17th, 2014

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

Researchers discover boron 'buckyball' July 14th, 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

Nanometrics Announces Upcoming Investor Events July 22nd, 2014

Bruker Awarded Fourth PeakForce Tapping Patent: AFM Mode Uniquely Combines Highest Resolution Imaging and Material Property Mapping July 22nd, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 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