Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


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

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

Jade Boyd
(713) 348-6778

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.

Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press


Iranian Scientists Present Graphic Model for Interaction of Anti-HIV Drug, HIV Virus November 20th, 2015

A simple, rapid test to help ensure safer meat November 19th, 2015

New Model Presented to Design, Produce Electronic Nanodevices November 6th, 2015

Are cars nanotube factories on wheels? Rice University, Paris colleagues: Study of lung cells suggests nanotubes are common pollutants October 20th, 2015


Stanford technology makes metal wires on solar cells nearly invisible to light November 27th, 2015

Dimensionality transition in a newly created material November 27th, 2015

Nanoparticles simplify DNA identification and quantification November 27th, 2015

A new form of real gold, almost as light as air November 27th, 2015

The latest news from around the world, FREE

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

Nanotechnology Now Featured Books


The Hunger Project

Car Brands
Buy website traffic