Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Space Industry and Business News .




TECH SPACE
Crystal-clear method for distinguishing between glass and fluids
by Staff Writers
Munich, Germany (SPX) May 29, 2013


Chemist Dr. Miriam Siebenburger has contributed to develop a new method to distinguish between a glassy and liquid state. Credit: HZB.

Many solids are produced from melting. Depending on how quickly they cool off, invariably, internal tensile stresses begin to build up. One example are Prince Rupert's Drops, or Dutch tears: you can hit their thick end with a hammer without breaking them while a slight pressure applied to their thin end is enough to shatter the entire tear.

The properties of safety or even gorilla glass are determined to a large extent by their internal tensile stresses. However, until now, our understanding of the unique characteristics exhibited by the condition of the glass as compared with a tough molten mass was spotty at best. Now, a collaboration of several German and Cretian research teams has offered a surprisingly simple model to explain the difference between glass and molten materials.

The HZB's contribution was by chemist Dr. Miriam Siebenburger of the Institute for Soft Matter and Functional Materials. Siebenburger came up with a rather elegant model system consisting of spherical plastic particles in aqueous solution (a mixture known as a suspension). Due to the tiny size of the particles - each having a diameter of around 150 nanometer - they float in the aqueous solution but never sediment.

The nanoparticles are covered by a thermosensitive "shell", whose thickness can be adjusted by varying the temperature, causing them to shrink and grow reversibly in a continuous manner.

This allows the chemist to convert her samples from a densely packaged "glass" into a less dense, more fluid state, in other words melt them down. Through a series of rheological measurements, Miriam Siebenburger was able to determine how quickly the internal tensions in her samples could relax at different particle packing densities.

For this purpose, she placed the samples in-between two parallel plates, which she counter-rotated relative to each other to produce shearing forces within the sample. After reaching a stationary state of shearing stress at a constant shearing rate, the rotating plates were actively stopped.

Next, the force it takes to stop the plates to zero shear rate, and which is a gauge for internal tensions, was measured. In the process, the critical difference between the fluid and glassy state became apparent:

Whereas the fluid tensions dissipated without a trace, a proportion of the tensions was maintained in the glassy state. The results are fitting nicely into the theoretical model developed by a group of Constance physicists who calculated the behavior of hard spheres at different packing densities.

What's more, measurements of the internal tensile stresses and dynamics of larger-sized particles (in the ?m range) by Cretian and Dusseldorf researchers and the molecular dynamics simulation of hard spheres by a team of researchers from Cologne and Mainz exhibit similar patterns of behavior.

The scientists are convinced that their findings apply to all types of glass that are created as a result of their high packing densities including metallic glass, which is mainly used for high-tech applications. The researchers' findings have now been published in the renowned scientific journal, Physical Review Letters.

DOI: 10.1103/PhysRevLett.110.215701 M. Ballauff, J. M. Brader, S. U. Egelhaaf, M. Fuchs, J. Horbach, N. Koumakis, M. Kruger, M. Laurati, K. J. Mutch, G. Petekidis, M. Siebenburger, Th. Voigtmann, and J. Zausch, "Residual Stresses in Glasses", Phys. Rev. Lett. 110, 215701 (2013).

.


Related Links
Helmholtz Association of German Research Centres
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TECH SPACE
Magnetic fingerprints of superfluid helium-3
Bundesanstalt, Germany (SPX) May 24, 2013
With their SQUIDs, low-temperature specialists of the Physikalisch-Technische Bundesanstalt (PTB) have made it possible for the magnetic moments of atoms of the rare isotope 3He (helium-3) to be measured with extreme sensitivity. With the aid of these sensors, highly sensitive nuclear resonance spectrometers were developed which have now provided deep insights into the state of matter at extreme ... read more


TECH SPACE
Helicopter-light-beams - a new tool for quantum optics

Just how secure is quantum cryptography

One Year Anniversary of KOMPSAT-3 Launch

Crystal-clear method for distinguishing between glass and fluids

TECH SPACE
Mutualink Platform to be Deployed by US DoD during JUICE 2013

General Dynamics to Deliver U.S. Army's Newest Tactical Ground Station Intelligence System

Boeing-built WGS-5 Satellite Enhances Tactical Communications for Warfighters

US Navy And Lockheed Martin Deliver Secure Communications Satellite For Mobile Users

TECH SPACE
First Light Angara Rocket Ready for Launch

Russia to launch 12 Proton-M rockets in 2013

Russian Spacecraft Manufacturer to Make Four Launches in 2014

Electric Propulsion

TECH SPACE
GPS solution provides three-minute tsunami alerts

Northrop Grumman Delivers 8,000th LN-100 Inertial Navigation System

NASA Builds Unusual Testbed for Analyzing X-ray Navigation Technologies

Pakistan adopts Chinese rival GPS satellite system

TECH SPACE
Slow progress on Unasur plans for a joint trainer aircraf

EADS sweetens KF-X offering

NASA's BARREL Mission Launches 20 Balloons

US F-15 crashes in Japan, pilot ejects safely

TECH SPACE
Milwaukee-York researchers forward quest for quantum computing

New Technique May Open Up an Era of Atomic-scale Semiconductor Devices

Bright Future For Photonic Quantum Computers

New magnetic graphene may revolutionize electronics

TECH SPACE
NASA Ships Sensors for Seafaring Satellite to France

NASA's Landsat Satellite Looks for a Cloud-Free View

Google team captures Galapagos Island beauty for maps

NASA Helps Pinpoint Glaciers' Role in Sea Level Rise

TECH SPACE
Fresh oil spill from Turkish tanker off Cape Town

Poland dumps old garbage system for greener setup

Wal-Mart fined $110 mn over hazardous waste

Frog once imported for pregnancy testing brought deadly amphibian disease to US




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement