Which plastic polymer is most acid-resistant?

[Ewokinarmor]

Hey, just a hypothetical question (I haven't been able to take Chem yet, but I do know the basic aspects of chemistry, so sorry if I sound like an idiot here). I'm not talking about any specific acid here, so let's just say it's submerged in H+ ions. My uneducated guess is polypropylene, as it appears to be the most nonpolar. Sorry about what is perhaps a stupid question, but any answers would be greatly appreciated.

Edited March 2, 2015 by Ewokinarmor

[John Cuthber]

Polyethylene and polypropylene are both pretty good. PTFE is a bit better. All the fluorine atoms round the carbon chain get in the way of any chemical attack.

[studiot]

When you start chemistry you will discover that acid resistance is more complicated (and therefore interesting).

 

John Cuthber was talking about hydroflouric acid, which is the strongest acid, but it will not dissolve certain metals.

 

To dissolve gold you need a mixture called aqua regia, which is not stronger the hydroflouric.

 

https://www.google.co.uk/search?hl=en-GB&source=hp&q=aqua+regia&gbv=2&oq=aqua+regia&gs_l=heirloom-hp.3..0l10.875.3016.0.4266.10.10.0.0.0.0.172.1063.5j5.10.0.msedr...0...1ac.1.34.heirloom-hp..0.10.1063.bUHpyAem4PI

 

I can't answer for polymers, I'll leave that to the professional polymer chemists here, but hydroflouric acid used to be supplied in rubber bottles because it attacks glass.

 

If this is for a school project then go to a local flooring company and ask them.

There are many fancy artificial polymers that have been developed specifically for acid resistance in industrial flooring.

Get some manufacturers' names and ring their technical departments, I'm sure they will also be glad to help.

 

 

Another complication is catalysis.

Many polymers are quite stable until a catalyst is added to a particular relaively weak acid.

The catalyst then allows the acid to break down the polymer.

Nature uses this extensively (there are many natural important polymers in biology) and has 'developed' enzymes for just this purpose.

 

Incidentally 'polymer' is just a term for multiple units of the same chemical structure joined together. The number of units does not have to be large or man made. Large numbers are often called 'high polymers' and made made ones 'synthetic high polymers'.

 

This is all meant to be value added general background and I wish you and exciting and fruitfull entry into the study of Chemistry.

 

Edited March 2, 2015 by studiot

[Sensei]

John Cuthber was talking about hydroflouric acid, which is the strongest acid, but it will not dissolve certain metals.

Quote from

http://en.wikipedia.org/wiki/Hydrofluoric_acid

 

"Hydrofluoric acid is classified as a weak acid because of its lower dissociation constant compared to the strong acids. "

 

"It is the only hydrohalic acid that is not considered a strong acid,"

[studiot]

Thank you for that correction sensei +1

[Ewokinarmor]

Alright, thanks guys! Sounds fascinating, can't wait for AP Chem

Edited March 3, 2015 by Ewokinarmor

[DrP]

QUOTE: "...Cuthber was talking about Hydrofluoric acid..."

 

No he wasn't, he was talking about PTFE. PolyTetraFluoroEthylene.

[studiot]

 

Posted Today, 12:27 PM

QUOTE: "...Cuthber was talking about Hydrofluoric acid..."

 

No he wasn't, he was talking about PTFE. PolyTetraFluoroEthylene.

 

Gosh I really screwed up that post didn't I?

 

Apologies all round.

[DrP]

I wouldn't beat yourself up over it... I'm sure you meant well...

[horsebox]

I've stored 40% HBr in HDPE containers for a couple of months and didn't notice any signs of reaction so HDPE has pretty good acid resistance. Teflon is better. They're just common plastics though, anyone know of specially designed plastics geared towards chemical resistance?

[CharonY]

I am not quite sure what you mean with "common" plastic as they were also designed to be chemically resistant. Anyway, off the top of my head I would also add PEEK and PVDF (though certainly not to fuming sulphuric acid).