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Author: Subject: Recovery of styrene monomer from polystyrene
Keras
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[*] posted on 28-4-2021 at 04:56
Recovery of styrene monomer from polystyrene


Folks,

I have (or rather: used to have) a one litre bottle of styrene, that I left in store somewhere. When I turned back to it, all the styrene had polymerised, so it’s now a bottle full of white polystyrene.

If I wanted to recover the monomer from its present form, what should I do? I read here that heating polystyrene at 400 °C over a MgO bed can led to around 70% styrene recovery. By chance, any other method you'd know that'd require less heat, maybe ?

Thanks.
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njl
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[*] posted on 28-4-2021 at 05:08


The gist of polystyrene to styrene monomer is mostly thermal cracking as far as I know. There are some catalysts like metal oxides (MgO) that can either increase recovery or lower the reaction temperature, but you will still have to use high heat. UC235 has a video on polystyrene cracking on youtube.



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draculic acid69
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[*] posted on 28-4-2021 at 06:07


I'm just guessing but 70% seems rather on the low side. Doesn't the uc235 video
Show a much higher yeild using no catalyst?
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[*] posted on 28-4-2021 at 07:31


Yields via pyrolysis are pretty good.

For some unknown reason, this video isn't starting at the beginning.

https://www.youtube.com/watch?v=6tEs7P6UUVQ

[Edited on 28-4-2021 by zed]
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unionised
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[*] posted on 28-4-2021 at 08:24


It used to be a classic school demo.
Just heating the stuff will give you styrene.

But, unless you have some hydroquinone or something to use as a polymerisation inhibitor, it will revert to a polymer again.

Also works with PMMA
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[*] posted on 28-4-2021 at 10:53


Quote: Originally posted by unionised  
It used to be a classic school demo.
Just heating the stuff will give you styrene.
But, unless you have some hydroquinone or something to use as a polymerisation inhibitor, it will revert to a polymer again.
Also works with PMMA


Oh, I have 125 g of hydroquinone I didn't know what to do with. Thanks a bunch of suggesting this!
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[*] posted on 28-4-2021 at 13:06


I think that's roughly enough for (literally) a ton of styrene.
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[*] posted on 28-4-2021 at 14:01


Quote: Originally posted by unionised  

Also works with PMMA


Yielding methyl methacrylate?




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zed
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[*] posted on 29-4-2021 at 03:27


Yup! I think I might have posted a procedure...once upon a time.

[Edited on 29-4-2021 by zed]
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[*] posted on 29-4-2021 at 04:50


Off topic to this thread, but what did you end up doing with it?




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[*] posted on 29-4-2021 at 21:37


Quote: Originally posted by unionised  
I think that's roughly enough for (literally) a ton of styrene.


Had I known (or guessed, rather) that before, I would've added a few mg of it directly to my styrene bottle in the first place.

Talk about late epiphanies… :p
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[*] posted on 30-4-2021 at 09:35


I've done this without any catalyst, bloody stinks and it broke my RBF on cooling. Didn't have any inhibitors to keep the product but it worked well enough with minimal thought put into it.

That said if the flask didn't break I probably would never have got it clean from all the charing.
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[*] posted on 30-4-2021 at 10:34


Quote: Originally posted by Swinfi2  
I've done this without any catalyst, bloody stinks and it broke my RBF on cooling.


Any idea why it broke?
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