Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Microscopic cracks spoil the transparency of glass, nano-researchers find

13.10.2003


The cloudy look on cleaned glass is scattered light, not streaks of dirt



A fundamental discovery about the behavior of cooling glass could have a significant impact on the glass- and plastic-making industries, say researchers at Lehigh University.
Himanshu Jain, Diamond chair and professor of materials science and engineering at Lehigh, says the breakthrough was made possible by a combination of nanoscopic science and an old-fashioned kitchen recipe.

When molten glass is blown rapidly to make articles of desired shape, Jain’s group found, its outermost surface, measuring a few nanometers in thickness, sustains microscopic fractures when it comes into contact with air. One nanometer equals one one-billionth of a meter.



These fractures are microns or nanometers in width and thus too small to be seen with the unaided eye, says Jain. But when they are exposed to an aggressive solution, such as a dishwashing soap, the cracks etch out, spread and begin to dissolve faster than the rest of the glass, leaving behind a dirty look that can not be cleaned away.

In reality, says Jain, the dirty look is merely light that is scattered by the numerous microscopic cracks.

Jain’s group described their findings in an article titled "Inhomogeneous evolution of a glass surface via free, rapid expansion" in the Oct. 6, 2003, issue of Applied Physics Letters.

Previously, says Jain, scientists and glass-makers had assumed that under force molten glass expanded in a uniform manner and that finished glass was a chemically durable, homogeneous material.

Jain has spent more than two decades studying the unorganized arrangements and unpredictable movements of atoms in glass’s non-crystalline structure.

Several years ago, he was asked by Unilever to figure out why, after being washed in a dishwasher, some wineglasses acquire a lined, milky look that can not be removed by further cleanings.

To solve the puzzle, Jain, his graduate student Anju Sharma, and Unilever collaborator Joseph O. Carnali, turned the prevailing assumptions about the properties of glass on their head and hypothesized that the surface of molten glass was solid and thus prone to cracking.

"We had to come up with a hypothesis because, using the traditional assumption that the surface was behaving like a liquid, we could not understand everything about the corrosion of the glass," he said.

With help from his 12-year-old daughter, Isha, Jain designed a home experiment to test his hypothesis.

The Jains started their experiment with a cooking pot. Using an Internet recipe for making hard candy, known by scientists as sucrose glass, they boiled a mixture of water and sugar, which mimics the molecular behavior of the soda and silica that are the main ingredients of commercial glassware.

When the hot syrup reached the consistency of viscous glass, Jain and his daughter used an empty ballpoint pen to simulate the blowing of glass.

When they studied the microstructure of the sucrose glass surface in detail, the Jains found tiny cracks, indicating that the surface had expanded not in a uniform fashion, like a liquid would, but in a non-uniform manner, as a solid would.

Encouraged by this initial observation, the Lehigh researchers conducted more sophisticated experiments in laboratory, blowing real glass and characterizing its expanding surface with electron microscopy.

"No one had imagined that the top nanometer or two of the surface was a solid," Jain said. "Our lab experiments had proved our hypothesis. Only the top of the surface fractured; the rest of the glass remained very homogeneous."

One factor contributing to the formation of the tiny cracks on the nano-surface, says Jain, is the fact that there is a very high temperature gradient at the glass surface.

Jain conducted his experiments using sucrose glass and real glass, but he believes plastics will behave similarly, although to a lesser degree, as plastic products are formed at lower temperatures.

"This is a quality-control issue for manufacturers," he said. "For nano-researchers, the lack of homogeneity on the nano-scale could be a serious problem that would need to be resolved as nanotechnology enters the market place."

A second paper by Jain and his colleagues, which describes the effect of manufacturing-induced corrosion on wineglasses and other commercial glassware, is scheduled to be published next week by the Journal of the American Ceramics Society.

Kurt Pfitzer | EurekAlert!

More articles from Materials Sciences:

nachricht A new tool for discovering nanoporous materials
23.05.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Did you know that packaging is becoming intelligent through flash systems?
23.05.2017 | Heraeus Noblelight GmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Camera on NASA's Lunar Orbiter survived 2014 meteoroid hit

29.05.2017 | Physics and Astronomy

Strathclyde-led research develops world's highest gain high-power laser amplifier

29.05.2017 | Physics and Astronomy

A 3-D look at the 2015 El Niño

29.05.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>