Sciencemadness Discussion Board

Chemical Resistance of Plastics

1281371269 - 9-11-2009 at 11:54

I found this link - it's a very well presented datasheet of the chemical resistivity of common plastics. It's the kind of thing that could be useful to print off and put on the lab wall.

http://chiron.no/pdf/Chemical_Resistance_of_Plastics.pdf

Can anyone comment on the accuracy?

hissingnoise - 9-11-2009 at 12:51

Damien Hirst on Meth?
Wrong question, sorry. . .
Its accuracy looks good!
Use teflon!


[Edited on 9-11-2009 by hissingnoise]

1281371269 - 9-11-2009 at 13:13

It gives every name for Teflon (FEP / TFE / PFA) apart from PTFE which is the one most widely used. Strange.

[Edited on 9-11-2009 by Mossydie]

Lambda-Eyde - 9-11-2009 at 13:39

Chiron is a well-reputed chemical company located in Norway, not far from where I live. I believe they have done their homework.

Attached is a pdf listing the chemical resistance of PP (polypropylene). It's a very long and detailed list, and I find it extremely useful when determining whether I should use blue or red caps for my Simax reagent bottles!

Attachment: Resistance of Polypropylene.pdf (228kB)
This file has been downloaded 849 times


Edit: Seems like the pdf is from Ace glass, but that only makes it more reliable, doesn't it? :P

[Edited on 9-11-2009 by Lambda-Eyde]

Formatik - 9-11-2009 at 14:44

Here's another thread on this: http://www.sciencemadness.org/whisper/viewthread.php?tid=118...

To comment on accuracy, I wouldn't trust the generalized charts as much as those which are more specific, for example, in that chart for the HDPE under "Acids strong and conc.", HDPE will not hold up to acids like red fuming HNO3, oleum, or chlorosulfonic acid. Even though there is a general compatability stated, it will get attacked. But even with more specific charts, it's best to check multiple tables. You can also find charts which are more specialized in the single plastic you are looking at.

S.C. Wack - 9-11-2009 at 20:42

http://www.nibco.com/assets/ChemGuide.pdf

starman - 9-11-2009 at 22:06

Quote: Originally posted by Formatik  
Here's another thread on this: http://www.sciencemadness.org/whisper/viewthread.php?tid=118...

To comment on accuracy, I wouldn't trust the generalized charts as much as those which are more specific, for example, in that chart for the HDPE under "Acids strong and conc.", HDPE will not hold up to acids like red fuming HNO3, oleum, or chlorosulfonic acid.


It does state in the key beneath the chart "not for oxidising acids" such as HNO3 you mentioned.Clear enough that one should seek clarification as to compatibility of an indivdual acid.Accurate enough IMO.

merrlin - 10-11-2009 at 00:39

Quote: Originally posted by Mossydie  
It gives every name for Teflon (FEP / TFE / PFA) apart from PTFE which is the one most widely used. Strange.

[Edited on 9-11-2009 by Mossydie]


Teflon is a trade name that has achieved generic use and although it is usually used in association with PTFE, it doesn't refer to a specific compound. Attached is some information on various fluoropolymers. I have seen disagreements between chemical compatiblilty charts that I have found on the web, so you may want to confirm compatibility by multiple sources. Compatibility itself is not always well defined. Some polymers may not be attacked by certain compounds but have a high enough absorption or permeability to cause problems. For example, PTFE has a permeability to helium that is about 1000 times greater than that of nylon. This typically isn't a problem unless you are trying to helium leak check a high vacuum system with PTFE seals.

Attachment: Pages from Technology of Fluoropolymers.pdf (457kB)
This file has been downloaded 3485 times

Formatik - 10-11-2009 at 12:43

Quote: Originally posted by starman  
It does state in the key beneath the chart "not for oxidising acids" such as HNO3 you mentioned.


That comment was aimed at Mossydie's chart, where nothing there warns of oxidizing acids. According to a few charts, HDPE can take up to 30% concentration HNO3 with a "satisfactory" rating.

Lambda-Eyde - 10-11-2009 at 13:26

Quote: Originally posted by Formatik  

That comment was aimed at Mossydie's chart, where nothing there warns of oxidizing acids. According to a few charts, HDPE can take up to 30% concentration HNO3 with a "satisfactory" rating.

I have seen 70 % HNO3 supplied in HDPE bottles, which leads me to believe the rating should be higher than "satisfactory"...

[Edited on 10-11-2009 by Lambda-Eyde]

Picric-A - 10-11-2009 at 13:32

All the conc (70%) nitric i buy is in HDPE bottles...
They are stained yellow however i see no furthur deteriation (sp?) than that...
the has stayed good for 2 yrs now and counting.

1281371269 - 10-11-2009 at 14:36

HDPE supposedly becomes brittle after long storage - but I have some 70% that was supplied in a black HDPE bottle and it's fine.

Formatik - 10-11-2009 at 15:13

Many charts I've seen indicate conc. HNO3 isn't recommended with HDPE, e.g.: Calpac lab link above gives this for 70% HNO3: "HDPE and LDPE at 20C° show some effect after 7 days. Both at 50C° show immediate damage and are not recommended."

But I personally don't trust conc. nitric in any plastic beyond teflon, a glass bottle of commercial 54% I have has a plastic cap, the acid is several years old (at least about 6 to 8) and the cap already shows signs of some attack. In the long term, I would rather be safe than sorry, even though I favor plastic.

smuv - 10-11-2009 at 16:57

I have seen very high purity 70% nitric acid provided from chem suppliers in nalgene bottles. When the bottle was empty I took it and am now storing >>70% nitric acid in it; 9 months and no issues. The plastic is clear/colorless with no yellowing.

lucky123 - 24-11-2009 at 17:55

I was wondering any plastics suitable for ethonal stills? Particularly pvc, cpvc, hdpe and pp irrigation pipe, ldpe tubing, upvc and pex pipe and pvdf tubing? I hear yes and no depending where you look so anyone know for sure which are best especially for making a fractional coulum where strong vapors will be at 95+ ethanol...

Lambda-Eyde - 25-11-2009 at 01:24

Quote: Originally posted by Mossydie  
HDPE supposedly becomes brittle after long storage - but I have some 70% that was supplied in a black HDPE bottle and it's fine.

HDPE does become brittle after years of exposure to sunlight. All my Merck agar boxes have the words "ACHTUNG: Licht macht kunststoff sprödel" on them! :D
I have also witnessed this in our school lab, where all the relatively "un-harmful" chemicals are kept in a cupboard with a glass window. I was taking a box of manganese dioxide out from the cupboard and the lid just crumbled into pieces as I tried to open it!
So keep HDPE boxes/bottles out of sunlight, people!

Panache - 25-11-2009 at 21:55

Quote: Originally posted by merrlin  
Quote: Originally posted by Mossydie  
It gives every name for Teflon (FEP / TFE / PFA) apart from PTFE which is the one most widely used. Strange.

[Edited on 9-11-2009 by Mossydie]

For example, PTFE has a permeability to helium that is about 1000 times greater than that of nylon. This typically isn't a problem unless you are trying to helium leak check a high vacuum system with PTFE seals.



Ha! I love stories like this, how long did you spend looking for the non-existent leak? Was the entire thing dismantled and reassembled?

JohnWW - 29-11-2009 at 14:35

Quote: Originally posted by Mossydie  
HDPE supposedly becomes brittle after long storage - but I have some 70% that was supplied in a black HDPE bottle and it's fine.
Black HDPE contains finely-divided graphite (lampblack), which absorbs all wavelengths of light, including well into the UV and IR. It ensures that UV light, which soon causes translucent polyethylene to become brittle and crumble, does not penetrate more than a few microns into the surface. This is why graphite-filled black polyethylene is used for irrigation pipes, black plastic sheeting, and black plastic water collection tanks.

merrlin - 2-12-2009 at 12:27

Quote: Originally posted by Panache  
Quote: Originally posted by merrlin  
Quote: Originally posted by Mossydie  
It gives every name for Teflon (FEP / TFE / PFA) apart from PTFE which is the one most widely used. Strange.

[Edited on 9-11-2009 by Mossydie]

For example, PTFE has a permeability to helium that is about 1000 times greater than that of nylon. This typically isn't a problem unless you are trying to helium leak check a high vacuum system with PTFE seals.



Ha! I love stories like this, how long did you spend looking for the non-existent leak? Was the entire thing dismantled and reassembled?


In this instance was fortunate to have been warned about the teflon/helium anomaly before having the opportunity to learn by experience.

lucky123 - 12-12-2009 at 19:17

So the black hdpe pipe would be a good choice I take it and what about cpvc and pex pipe? I hear pex pipe due to the crosslinkage increases chemical resistance and temperature ratings. And from an earlier post above rigid pvc pipe (grey pipe at harware store) would work. So what is this talk about plasticizers and people having them leeched into their spirits? What plastics would cause this problem???