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Author: Subject: convert PET plastic into HDPE
nikotyna1939
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[*] posted on 16-3-2019 at 20:15
convert PET plastic into HDPE


is it possible to convert polyethylene terephthalate into HDPE
if you know just how the process
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j_sum1
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[*] posted on 16-3-2019 at 20:33


I think if you look at the structures you will have your answer.
Anything is possible if you are prepared to break your polymer down to elemental form. It's just a stupid, energy-inefficient idea.
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[*] posted on 17-3-2019 at 01:58


To be fair, the names suggest that it should be easy.
It's not.
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XeonTheMGPony
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[*] posted on 17-3-2019 at 05:43


Quote: Originally posted by unionised  
To be fair, the names suggest that it should be easy.
It's not.


Like most things.

OP: Study plastics a bit more, there is allot of nuanced complexity behind seemingly simple things!
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[*] posted on 17-3-2019 at 08:23


Just to let you know, "a lot" is two words.
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PirateDocBrown
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[*] posted on 17-3-2019 at 13:28


Sigh.

First of all, why would you want to do that? Bulk polymers like these are inexpensive commodities.

Second, these two are not actually related to each other.

HDPE is polyethylene. It's made by free-radical polymerization of a single ethylene monomer.

PET is a copolymer, made with two monomers, terephthalic acid, (ie p-phthalic acid) and ethylene glycol. It's a condensation polymer, not a free-radical, made by using heat to remove water.

So, to answer your question, you'd hydrolyze the PET, distill out the ethylene glycol, dehydrate that to ethylene oxide, then reduce that to ethylene. Then, use free-radical polymerization to make PE.

Honestly, I have no idea how to do that reduction, as ethylene is the precursor to ethylene oxide, not the other way around.

You wanna make PE, make it from ethylene, like it's meant to be. Finding some roundabout way to get ethylene is just pointless.




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nikotyna1939
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[*] posted on 18-3-2019 at 18:58


i just want know because hdpe is more expensive than pet

[Edited on 19-3-2019 by nikotyna1939]
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PirateDocBrown
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[*] posted on 19-3-2019 at 02:21


HDPE is made under pretty extreme conditions, for a home chemist, ie high temps and pressure. You're best recycling used HDPE materials as a source.



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[*] posted on 19-3-2019 at 04:06


Quote: Originally posted by nikotyna1939  
i just want know because hdpe is more expensive than pet

[Edited on 19-3-2019 by nikotyna1939]


Good point
It's more valued than PET at recycling centers too
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[*] posted on 26-3-2019 at 17:49


HDPE is reputed to be recyclable up to 10 times. PET perhaps once or twice.

Big polluter PET. Makes a decent Pop Bottle. Those Pop bottles, once emptied of Pop, might be used in some places to purify water. Very transparent to UV light. Sunlight goes right through the bottle walls, and sterilizes the contained water. PET doesn't stand up to direct sunlight forever, however.

Most PET is spun into thread and woven into polyester clothing, and here is where the polluting part come in.
When washed, that fabric sheds microscopic PET fragments into the wash water, by which vehicle it traverses the entire eco-system.

https://ensia.com/features/microfibers/

Hard to stop. Used bottles are basically free stuff. Cotton, luxurious Cotton...Well, that ain't free.

[Edited on 27-3-2019 by zed]
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