Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Nanomechanics: New Test Measures Key Properties of Polymer Thin Films and Membranes

Nanomechanical measurements (model system and microimage of typical specimen). a) thin rigid film on elastic substrate b) initial strain induces surface wrinkles parallel to stress c) additional strain induces regular pattern of cracks in the film d) typical specimen imaged with optical profilometer (280 X 210 micrometers.)
Credit: Chung, Lee/NIST
Nanomechanical measurements (model system and microimage of typical specimen). a) thin rigid film on elastic substrate b) initial strain induces surface wrinkles parallel to stress c) additional strain induces regular pattern of cracks in the film d) typical specimen imaged with optical profilometer (280 X 210 micrometers.)

Credit: Chung, Lee/NIST

Abstract:
Researchers at the National Institute of Standards and Technology (NIST) have demonstrated* a measurement technique that reliably determines three fundamental mechanical properties of near-nanoscale films. The technique, which highlights the challenge of making mechanical measurements on an object with at least one dimension comparable to the size of a virus, should enable better design and engineering for a variety of thin-film technologies, particularly reverse-osmosis membranes for water purification.

Nanomechanics: New Test Measures Key Properties of Polymer Thin Films and Membranes

Gaithersburg, MD | Posted on July 21st, 2011

Reverse-osmosis membranes, explains NIST researcher Chris Stafford, are an interesting challenge for the materials scientist. The membranes are used in water purification systems—a polyamide film no more than 200 nanometers thick backed by a thicker, porous support layer. Water holding dissolved salts or other contaminants is forced against one side of the membrane at substantial pressures up to about a thousand psi (roughly 7 megapascal), and comes out the other side leaving most of the impurities behind. The mechanical integrity of the membrane is obviously essential—it can't tear or develop pinhole leaks under the pressure—but engineers lacked a good way to measure the strength and breaking point, under stress, of these extremely thin films.

The NIST technique builds on earlier work by the team that demonstrated that you can reliably determine Young's modulus—a measure of stiffness or elasticity—for thin and ultrathin films by bonding it to a piece of silicon rubber, and then carefully stretching it in one direction. The film will develop a regularly spaced pattern of wrinkles (try it with a piece of plastic wrap), and the spacing of the wrinkles, the amount of stretch and some math gives you the modulus. In the new work, they basically pull harder until the film starts developing minute cracks crosswise to the tension. These too, it turns out, occur in regular patterns, and the spacing can be analyzed to determine both the fracture strength and the onset fracture strain, or the failure point, of the film.

Applying their technique to study the effect of chlorine on reverse-osmosis membranes, the team uncovered a puzzle. Chlorine in the water is known to cause a progressive deterioration in membrane performance, generally thought to be the result of prolonged chemical attack by the chlorine. Not so, according to the NIST team. "Chemically the chlorine attack is pretty quick," says Stafford. Spectroscopic chemical analysis showed that all the chemical damage from chlorine exposure happens in the first few hours. Tests using the wrinkle-crack method, however, show that the mechanical properties degrade continuously—the material becoming more and more stiff, brittle and weak—up to the longest duration tested, 10 days. "It may be an aging effect in polymers," says Stafford. "We're continuing to study that to figure out what's going on in there, because it's a real measurement challenge to get in on that length scale to follow the structure over time."

The project is part of a broader NIST program to study materials issues related to sustainable technologies like water purification, but the research team notes that the wrinkle-crack method itself would be broadly applicable to mechanical studies of almost any nanoscale thin film in fields as diverse as artificial skin, flexible electronics, thin-film sensors, fuel cells and photovoltaics.

* J.Y. Chung, J.-H. Lee, K.L. Beers and C.M. Stafford. Stiffness, strength, and ductility of nanoscale thin films and membranes - A combined wrinkling-cracking methodology. Nano Letters. Articles ASAP (As Soon As Publishable), July 15, 2011. DOI: 10.1021/nl201764b.

####

About NIST
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

For more information, please click here

Contacts:
Michael Baum
301-975-2763

Copyright © NIST

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

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Physicists build reversible laser tractor beam October 20th, 2014

Removal of Limitations of Composites at Superheat Temperatures October 20th, 2014

Laboratories

HP Supercomputer at NREL Garners Top Honor October 19th, 2014

ORNL research reveals unique capabilities of 3-D printing October 15th, 2014

Scientists Map Key Moment in Assembly of DNA-Splitting Molecular Machine: Crucial steps and surprising structures revealed in the genesis of the enzyme that divides the DNA double helix during cell replication October 15th, 2014

Thin films

Nanocoatings Market By Product Is Expected To Reach USD 8.17 Billion By 2020: Grand View Research, Inc. October 15th, 2014

3x improvement in wear resistance from Carbodeon nanodiamond-enhanced electroless nickel plating October 14th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Imaging electric charge propagating along microbial nanowires October 20th, 2014

HP Supercomputer at NREL Garners Top Honor October 19th, 2014

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Discoveries

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Physicists build reversible laser tractor beam October 20th, 2014

Removal of Limitations of Composites at Superheat Temperatures October 20th, 2014

Announcements

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Physicists build reversible laser tractor beam October 20th, 2014

Removal of Limitations of Composites at Superheat Temperatures October 20th, 2014

Water

New Nanocomposites Help Elimination of Toxic Dyes October 15th, 2014

Fast, cheap nanomanufacturing: Arrays of tiny conical tips that eject ionized materials could fabricate nanoscale devices cheaply October 4th, 2014

Production of Filters for Separation of Water from Petroleum Products in Iran October 1st, 2014

Malvern Instruments & Aurora Water conference presentation illustrates value and cost-saving potential of on-line zeta potential in water treatment: 2014 RMSAWWA/RMWEA Joint Annual Conference, Albuquerque, New Mexico, USA September 7th – 10th September 3rd, 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