Recycling Plastic With Liquid Nitrogen

Ln2

Recycling 3D printer filament isn’t a new idea, and in fact there are quite a few devices out there that will take chunks ABS, PLA, or just about any other thermoplastic and turn them into printer filament. The problem comes when someone mentions recycling plastic parts and turning them into filament ready to be used again. Plastics can only be recycled so many times, and there’s also the problem of grinding up your octopodes and companion cubes into something a filament extruder will accept.

The solution, it appears, is to freeze the plastic parts to be recycled before grinding them up. Chopping up plastic parts at room temperature imparts a lot of energy into the plastic before breaking. Freezing the parts to below their brittle transition temperature means the resulting chips will have clean cuts, something much more amenable to the mechanics of filament extruders.

The setup for this experiment consisted of cooling PLA plastic with liquid nitrogen and putting the frozen parts in a cheap, As Seen On TV blender. The resulting chips were smaller than the plastic pellets found in injection molding manufacturing plants, but will feed into the extruder well enough.

Liquid nitrogen might be overkill in this case; the goal is to cool the plastic down below its brittle transition temperature, which for most plastics is about -40° (420° R). Dry ice will do the job just as well, and is also available at most Walmarts.



		

Liquid nitrogen (finally) makes an Arduino project cool

At $1.5 a liter in Moscow, [Michail] couldn’t resist buying some liquid nitrogen for himself. He thought that because Arduinos were quite popular among geeks, he’d try to overclock one while bringing its temperature down to -196°C/-320°F.

To check the ATmega was still working correctly, [Michail] designed several stability tests: SRAM read/write, flash read, arithmetic math and program flow tests (code with some conditionals). He used a standard HD44780 LCD to view the tests results but also an LED, blinking the number of the test it would have failed. The Arduino was externally clocked by a TTL-logic based square signal generator he designed, which can produce a clock between 16 and 100MHz. It turns out that you can run an Arduino at 65.3MHz when it is cooled with liquid nitrogen!

[Michail]‘s article also explains what happens to the different on-board components when cooled with LN2: electrolytic capacitors becomes virtually non-existent, X7R capacitors’ impedance drop by 2/3, silicon diodes voltage drop increase by 50% and LED’s colors change. Check out the video below:

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Dropping the nitrogen bomb in science class

We took Geology in college. It was pretty cool learning about the hardness of different minerals. But there were no explosions involved. We’re not entirely sure what this class is, perhaps Chemistry, maybe Physics, but we want in. [Dr. Roy Lowry] wows the class with a bomb made of liquid nitrogen. The demonstration was part of his lecture at Plymouth University.

A small explosion is cool, but [Roy] knows how to add the wow factor. To make the bomb he filled a one liter plastic bottle about 1/3 of the way with liquid nitrogen. After tightly sealing the cap it was dropped in that garbage can which had a pool of warm water in it. Before quickly running away he and his assistant dumped a few garbage bags of ping-pong balls on top of it all. When the plastic bottle bursts under the pressure of the expanding gas it sends the garbage can about six feet into the air and floods the room with bouncing white balls. See the whole presentation for yourself in the clip after the break and don’t forget the sound so you can catch the oohs and aahs at the end.

Looks like a Hackerspace recruitment tool if we’ve ever seen one.

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Measuring how components react to extremely cold temperatures

[Shahriar Shahramian] is playing with some liquid nitrogen in order to see how various components react to extremely low temperatures. After the break you will find forty-one minutes of video in which he conducts and explains each experiment. This does have practical applications. If you’re designing hardware for use in space you definitely need to know how the hardware will be affected. We’ve actually seen test rigs built for this very purpose.

During the presentation he doesn’t water down the concepts observed, including the equations governing each reaction to temperature change. If you’re in the mood for a little bit lighter faire you should check out some of the liquid nitrogen cooking hacks like this super-cold cocktail pops project.

 

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Hot enough for ya? Super-cold cocktail-pops will help

The staff of Instructables know how to cut loose and cool off in this already-too-hot summer. They’re making their own popsicles out of cocktails. If only everyone were lucky enough to have employers who endorse these kinds of projects at work.

So the problem here is the the freezing point of liquor. Your margarita, daiquiri, strawberry with champagne, white russian and other favorites just aren’t ever going to solidify in a run-of-the-mill freezer because zero degrees Fahrenheit just won’t cut it. So the big guns were brought to bear. The cocktail-pops were lined up in a container and dowsed with liquid nitrogen.

The substance boils off at around -321 F, more than cold enough to quickly freeze these alcoholic goodies. But use caution. After they’ve been frozen you need to throw them in the freezer to warm them up. The first guinea pigs burned their tongues when trying to lick the pops too soon.

Don’t want to buy your liquid nitrogen? Why not just make your own?

Making liquid nitrogen at home


If you’ve got some time to scour eBay and $500 sitting around you can build your own liquid nitrogen plant. [Ben Krasnow] figured it all out for you and estimates he can produce a liter of the stuff for around $1.15. The process depends on a membrane to separate nitrogen from the other materials in the air around us and a cryocooler to get the gas cold enough to condense into a liquid. Other than atmospheric air, you need to pump in electricity. About 9.6 kWh per liter… yikes! Is your human hair solar panel up to that?

Anyway, once you’re up and running you can make yourself some ice cream or possibly save the world from oily destruction.

[Thanks Chris]

BP oil blunders

We received a very interesting “hack” today from our good friend [Jonny Dryer] that really got us thinking, but first a little background.

For those that live only inside of a box on top of a mountain (we know who you are), there was an explosion of a British Petroleum oil rig about 40 miles southeast of Venice, LA. Being proclaimed by Carol Browner as “probably the biggest environmental disaster” – stated a month after the accident.

And the oil is still spewing. Now, we’re not ones for criticizing how this event is being handled; no, we left it to the experts.

Back to our point, [Jonny Dryer's] sent us his plan for slowing the oil spill, by using liquid nitrogen, pretty genius if you ask us. And we were wondering what possible solutions other readers had come up with? Share your thoughts on this situation in the comments.