Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


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


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 From ancient fossils to future cars
21.10.2016 | University of California - Riverside

nachricht Study explains strength gap between graphene, carbon fiber
20.10.2016 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>