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Recycling Soda Bottles Experiments Answered

Test 1: heat gun, "high setting"  Plastic Coke bottle SOFTENS + shrinks                                                                  -  at about 250F *
Test 2: Heat gun " low setting** " Plastic coke bottle MELTS enough to  make gooey threads , and bubbles   -   at 450 to 500 F

*according to a cheapy harborfreight laser thermometer. Not sure just how accurate it is in the 250  to 500F range. This device seems to read 5 degrees high at the 100F range.

** ironically, the temp is higher on the "low" setting. When the fan is moving less air, that air is hotter.

One of the tricks, I imagine, might be to fully melt the plastic without burning it.  

Suggestions welcome. Further results will follow.

Discussions

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Kiteman

5 years ago

You know, if you're doing a series of tests, your methods and results would make a perfectly valid instructable - A step for each test, photos or videos of the results etc.

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Toga_DanKiteman

Reply 5 years ago

I might get around to doing an -ible. Lately, though, full photo documentation seems to be the straw to break the camels back. I'm just almost overtasked. Kinda wishing for a videographer or googleglass, or gopro strapped to my head.

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Downunder35m

5 years ago

Soda bottles are usually made from PET a material that is easy to form bad hard to recyle.

Similar to Nylon it absorbs small amounts of moiture, which makes it very hard to melt them together again.

The only two options I know that allow a proper recyling of PET:
Melting a vacuum chanber to prevent oxidization.

This method requires the material to be compressed during heating and results in a solid block of plastic - which is then shredded into tin pieces that are dry and ready for the use in extrusion machines.


Shredding the material first into fine pieces allows the use of a simple drying furnace to remove the remaining moisture, again allowing the material to be extruded.

It is not possible (to my knowledge) to melt PET like wax for example.
Once it reaches meting temp the pieces will stay together and further heat will damage the properties of the plastic.
Fleece fabric is produced by heating recyled PET and extruding it onto a spinning disk or through fine nozzles in an airstream.
Since PET is also resistent again most obtainable solvents you might need another target for your recycling project, maybe plastic bags instead?

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Toga_DanDownunder35m

Reply 5 years ago

RE: Oxidation,

I'm thinkin of sealing plastic in chamber with dry ice. Let the dry ice gasify, then melt the plastic. Thus the chamber is full of CO2, preventing oxidation. I'm a bit nervous tho, to heat a sealed, or semi sealed container. Perhaps I could set up a vacuum chamber, however.

When the plastic is shredded before heating, the heat is crucial to drying, I suppose?

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Downunder35mToga_Dan

Reply 5 years ago

The heating is used for the drying , think of it like silica gel.

Without some heat you simply can't remove the moisture out of the plastic.

The discolorations and brittleness is due to oxidazition and to much heat, you only have a very smal window of operation here.

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Toga_Dan

5 years ago

TEST 3:

propane torch

Slowly bringing torch in closer, keeping it circling around on the bottle, when the bottle finally ignited, I took the torch away. Flames went out, and thermometer indicated about 600F. At this point the bottle got rather thoroughly melty. Parts of it went caramel color. Where it completely melted, it is white. Rather brittle throughout.

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Kiteman

5 years ago

Did you see any changes in colour, or in the properties of thd cooled plastic?

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Toga_DanKiteman

Reply 5 years ago

Plastic went a bit white when it reached slightly bubbly temp(four hundred +somethin) Haven't really done impact + flex test on that sample.