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Author: Subject: PET + ammonia. white powder
vano
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[*] posted on 17-1-2021 at 04:53
PET + ammonia. white powder


Hi. Sometimes i store ammonia solution on PET bottle. A few days ago I poured all the ammonia solution into a HDPE bottle. Of course i filtered it. And I collected this white powder. The particles are very small. What do you think is it a PET powder? or other organic compound(Terephthalic acid or ammonia salt).

[Edited on 17-1-2021 by vano]

[Edited on 17-1-2021 by vano]
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vano
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[*] posted on 17-1-2021 at 04:59


I found answer
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Mateo_swe
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[*] posted on 17-1-2021 at 12:51


I guess you found out that Ammonia should not be stored in PET bottles but i reply if anybody else also need to know.
Check solvent comparability with plastics before storing in different plastic bottles or containers.
Ammonia slowly dissolves certain plastics, like PET.
Some solvents and chemicals store fine in PET bottles but check comparability before using them.
Just google solvent comparability chart and you will find a lot of them.

You can watch this video on YT for some examples of what not to store in PET bottles and some solvents that can be stored in PET.
https://www.youtube.com/watch?v=E9Snse16qkE
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symboom
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[*] posted on 18-1-2021 at 01:43


Oh that's interesting that ammonia attacks some plastics I always thought plastic was much more chemical resistant than that I wonder 8f that can be exploited in reprocessing plastic.



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Boffis
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[*] posted on 18-1-2021 at 05:59


There's a whole thread on this somewhere on SM that followed from one members observasion that PET bottles disintegrate when used to store ammonia solution but interesting above the liquid level first. This lead to my own experiments into the preparation terephthalamide by exposing PET to ammonia fumes. It works but the product is difficult to purify. However by leach with dilute acid and dilute alkali you can remove the half amide bt the incompletely hydrolyses polymer can't be separated by any means available to me.

Check out the bottom part of this thread and the subsequent pages:
http://www.sciencemadness.org/talk/viewthread.php?tid=63196
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[*] posted on 19-1-2021 at 04:16


Few years ago I stored some chemicals in plastic PET bottles. I found that PET bottles can be permanently destroyed by 30% hydrochloric acid (it turns into pearl like- colour, become very brittle). With ammonia bottle is thinner and thinner during time and some small holes may occur later. Strong bases solutions (NaOH, KOH) destroying bottles within a week. However I still have 37% battery acid on the shelf in my garage (about 10 years) and no changes occur.

HCl_NH3.jpg - 398kB HCl2.jpg - 290kB

[Edited on 19-1-2021 by Piroz]
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draculic acid69
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[*] posted on 26-1-2021 at 06:44


Quote: Originally posted by symboom  
Oh that's interesting that ammonia attacks some plastics I always thought plastic was much more chemical resistant than that I wonder 8f that can be exploited in reprocessing plastic.


Yes it can.basically the ammonia is just a strong reactive base hydrolyzing the ester that is pet forming ammonia terepthalate and ethylene glycol I guess.on paper it's how it should be in reality it could possibly just be a solvent that dissolves pet but I doubt it's just that. I know that pet can be recycled back to its starting compounds by ester hydrolysis with NaOH. I've left conc. caustic soda (60%) in pet bottles and eventually it just dissolves the pet at room temperature
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vano
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[*] posted on 26-1-2021 at 07:26


Quote: Originally posted by Piroz  
Few years ago I stored some chemicals in plastic PET bottles. I found that PET bottles can be permanently destroyed by 30% hydrochloric acid (it turns into pearl like- colour, become very brittle). With ammonia bottle is thinner and thinner during time and some small holes may occur later. Strong bases solutions (NaOH, KOH) destroying bottles within a week. However I still have 37% battery acid on the shelf in my garage (about 10 years) and no changes occur.



[Edited on 19-1-2021 by Piroz]

My PET was very white. I also stored concentrated hydrochloric acid in a PET bottle, however, the color has not changed
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solo
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[*] posted on 26-1-2021 at 19:08


......here is a helpful guide regarding plastics reactivity with a list of solvents, a list which may already be posted someplace....solo

https://www.plasticsintl.com/chemical-resistance-chart




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Antiswat
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[*] posted on 28-1-2021 at 02:43


ammonium terephthalate should be interesting in terms of thermal decomposition. theres oftenly interesting byproducts from decomposing ammonium salts. and that ammonia reacts somewhat readily with PET just makes it more interesting
i believe pyrolysis is used on the sodium salt to try to get something useful out of it, im sure the ammonium salt would be much more interesting to work with in that regard




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draculic acid69
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[*] posted on 28-1-2021 at 22:25


Quote: Originally posted by Antiswat  
ammonium terephthalate should be interesting in terms of thermal decomposition. theres oftenly interesting byproducts from decomposing ammonium salts. and that ammonia reacts somewhat readily with PET just makes it more interesting
i believe pyrolysis is used on the sodium salt to try to get something useful out of it, im sure the ammonium salt would be much more interesting to work with in that regard


What is the product of the sodium terepthalate thing your talking about.
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