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Author: Subject: Distinguishing plastics without analysis?
Draeger
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[*] posted on 14-3-2020 at 06:25
Distinguishing plastics without analysis?


So, I have some plastic test tubes laying around that I bought a very long time ago, and I have no idea out of which plastic they are made.

Is there any way to find out without chemically analyzing them?

[Edited on 14-3-2020 by Draeger]




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH, NaHCO3, MnCl2, MnCO3, CuSO4, FeSO4, aq. 30-33% HCl, NaClO, aq. 9;5% ammonia, aq. 94-96% H2SO4, aq. 3% H2O2,

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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UC235
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[*] posted on 14-3-2020 at 06:45


Yes, there's only a few common plastics used for this sort of thing and they have different physical properties. Without even looking, my guess would be polypropylene which is widely used for plastic lab disposables.

What do they look like? Are they opaue, hazy and translucent, or clear? Are they hard and "glassy" or do they have give to them?
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Draeger
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[*] posted on 14-3-2020 at 10:28


Quote: Originally posted by UC235  
Yes, there's only a few common plastics used for this sort of thing and they have different physical properties. Without even looking, my guess would be polypropylene which is widely used for plastic lab disposables.

What do they look like? Are they opaue, hazy and translucent, or clear? Are they hard and "glassy" or do they have give to them?


Here's a picture of one of them.
They also have a very opaque, blue cap, similar to the cap of the water bottle in the picture.

The test tube itself feels hard, but it definitely doesn't act like glass. It is much more stable, and I could probably only break it by hitting it with a hammer or doing something of similar or greater force. The tip, on the other hand, has elastic properties and you can bend it with some force without it breaking or permanently being changed.

[Edited on 14-3-2020 by Draeger]




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH, NaHCO3, MnCl2, MnCO3, CuSO4, FeSO4, aq. 30-33% HCl, NaClO, aq. 9;5% ammonia, aq. 94-96% H2SO4, aq. 3% H2O2,

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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Deathunter88
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[*] posted on 15-3-2020 at 00:20


Looks like polycarbonate to me, can you send a clearer picture.
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Draeger
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[*] posted on 15-3-2020 at 05:04


Quote: Originally posted by Deathunter88  
Looks like polycarbonate to me, can you send a clearer picture.



Here's a clearer one. Might also be slightly corroded by ethanol I had in it for years when I didn't know ethanol ate some plastics.

[Edited on 15-3-2020 by Draeger]




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH, NaHCO3, MnCl2, MnCO3, CuSO4, FeSO4, aq. 30-33% HCl, NaClO, aq. 9;5% ammonia, aq. 94-96% H2SO4, aq. 3% H2O2,

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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Heptylene
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[*] posted on 15-3-2020 at 06:51


It could also be polystyrene or PET. If you can afford to destroy one, try smashing it. It it shatters easily it's likely to be polystyrene. Polycarbonate is impact resistant and won't shatter. PET won't shatter either.
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Draeger
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[*] posted on 15-3-2020 at 07:11


Quote: Originally posted by Heptylene  
It could also be polystyrene or PET. If you can afford to destroy one, try smashing it. It it shatters easily it's likely to be polystyrene. Polycarbonate is impact resistant and won't shatter. PET won't shatter either.

Since they were visibly corroded by the ethanol and they looked like hitting them with a hammer would break them, I very much assume that it is polystyrene. Thank you all for your help.




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH, NaHCO3, MnCl2, MnCO3, CuSO4, FeSO4, aq. 30-33% HCl, NaClO, aq. 9;5% ammonia, aq. 94-96% H2SO4, aq. 3% H2O2,

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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Morgan
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[*] posted on 15-3-2020 at 07:36


Maybe see how a small spot on the tube reacts with acetone if you think it's polystyrene.
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TheMrbunGee
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[*] posted on 15-3-2020 at 14:02


These are polystyrene. Have had too many incidents with acetone, I can now tell by the look, at least out of several common ones.



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UC235
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[*] posted on 15-3-2020 at 20:10


Acetone will trash polystyrene. You could also heat it with a torch. The smell of styrene is unmistakable.
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yobbo II
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[*] posted on 16-3-2020 at 15:36



Could be perspex (metamethcrylate?)

Poly(methyl 2-methylpropenoate)

Yob
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DavidJR
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[*] posted on 16-3-2020 at 16:08


I think that's almost certainly polystyrene. IMO polystyrene containers are basically trash and should be avoided.
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