Materials

Revolutionary technique produces injection-molded glass objects

Revolutionary technique produc...
Examples of objects made using the new process, in their initial polymer (white) and final quartz glass (clear) forms
Examples of objects made using the new process, in their initial polymer (white) and final quartz glass (clear) forms
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Examples of objects made using the new process, in their initial polymer (white) and final quartz glass (clear) forms
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Examples of objects made using the new process, in their initial polymer (white) and final quartz glass (clear) forms

Plastic is a lot easier to work with than glass, which is one of the reasons it's used so much more often. That may be about to change, though, thanks to a new process that allows glass to be injection-molded – just like plastic.

The technology was developed by a team at Germany's University of Freiburg, led by Drs. Bastian E. Rapp and Frederick Kotz. It's being commercialized under the name of Glassomer.

The process begins with small polymer granules, each one of which has tiny silica glass particles dispersed within it. These granules are poured into a standard injection molding machine that melts them, and then injects the molten polymer into a mold. Once the polymer has cooled and hardened, the item is ejected out of the mold. At this point, it still looks like it's made of regular plastic.

After being washed in water and placed in a 600 ºC (1,112 ºF) oven, however, all of the polymer is washed out or burned away – this leaves only the linked glass particles behind. When the item is then heated to 1,300 ºC (2,372 ºF), those particles fuse together via a process known as sintering, forming a pure quartz glass finished product.

"The particles basically smoothly flow into each other," Kotz tells us. "The component however stays in shape and just shrinks by a factor of around 15 percent in each direction."

Not only does the technology potentially allow for complex, detailed items to be quickly made out of glass in large quantities, but it also doesn't require the 2,000 ºC (3,632 ºF) temperature that's required to melt regular glass – this means it's considerably more energy efficient than conventional glass-good manufacturing methods. And as an added bonus, the polymer binder that is washed out of the items can be reused.

"For decades, glass has often been the second choice when it comes to materials in manufacturing processes because its formation is too complicated, energy-intensive and unsuitable for producing high-resolution structures," says Rapp. "Polymers, on the other hand, allow all of this, but their physical, optical, chemical and thermal properties are inferior to glass. As a result, we have combined polymer and glass processing. Our process will allow us to quickly and cost-effectively replace both mass-produced products and complex polymer structures and components with glass."

The new technique is described in a paper that was recently published in the journal Science.

Sources: University of Freiburg, Glassomer, American Association for the Advancement of Science via EurekAlert

9 comments
9 comments
TechGazer
This might allow some interesting options for optical components. They could layer different types of glass (different refraction properties) before sintering. If the result is still porous, applying liquid polymer might offer even more options for changing optical properties.
Mike Trites
This is one of the most exciting things I've read about in a long time. I'd love to see more high quality products that don't rely on environmentally harmful polymers, which tend to feel cheap and flimsy.
AryehZelasko
OK. Plastics generally do not break. Glass does. Is this new glass as none breakable as plastic? How do they compare in weight? Can you make a water bottle from it? I remember when glass water bottles for "coolers" were replaced by plastic because they weighted significantly less.
Worzel
First question that comes to mind, is, how are the silica glass particles produced? Does the glass to produce them, first have to be melted?
If so, then the alleged savings dont exist, even if the finished products, dont require the same energy as melting glass would have.
The next question, is, how do the particles meet and fuse, if they are surrounded by polymer, so that when the polymer is removed, the result isn't just a small pile of glass particles?
The process must work, but the bottom line is, how does the cost compare with polymer? Thats the first question that will be asked if a product is being considered for manufacture. With a polymer, the product is moulded, and ejected. This system has two more processes before the finished product is available. That must introduce extra costs.
To get a manufacturer to change materials for a product already being made in polymer to make it in glass, and invest in new equipment, there would have to be a long term cost saving as an incentive.
michael_dowling
"The component however stays in shape and just shrinks by a factor of around 15 percent in each direction." I guess if the part doesn't have to be on a 1 to 1 scale,this technique would be quite useful.
Kpar
Glass has a number of properties v. polymers that make this an interesting experiment. A couple of things- how closely can the "shrinkage" be controlled? Also, is there a way to control the brittleness of the glass? Can these objects be tempered?

I await more results from this- it could get very interesting.
Expanded Viewpoint
Another waste of time, effort and money. Glass is very brittle, and its strength is not very great, so I really don't see where it could have much, if any, advantage in replacing plastics. Running two glass gears together, at even a moderate rate of speed, will require a constant flow of clean lubricant, because any wear particles coming off of the gears will abrade even MORE particles until the gear teeth are worn down to the breaking point. That is why engines and transmissions have replaceable filters.
And, let's not forget about any shock loading that may occur! Plastics are pretty forgiving in that department, where glass certainly is not. When someone can come up with a part that is made of glass instead of plastic, and it exceeds all of the specs and parameters of plastic, let me know.
Karmudjun
Nice article Ben, and it follows the journal very well. This new technique - if affordable - may make it possible to remove BPA and other plasticizers from our food supply. Inherent in that is the energy savings v. retooling costs v. consumer demand. This could be a game-changer for the glass manufacturers. I could not see the nanocomposite ingredients or names - I would hope any residue would be free of endocrine disruptors. It would be a shame to have a new product prove cheaper, more environmentally friendly, larger profit margin, and equally concerning for human health as our ubiquitous plastics.
Worzel
Anyone considering that glass is too brittle, should bear in mind that there is bullet proof glass, which is far from brittle, and very strong.