Sciencemadness Discussion Board

Chemical resistance of materials

tjax - 18-9-2006 at 09:14

Hi everybody, this is my first post on this board.

I need a trustable and accurate source for chemical resistance charts. I launched a search on previous posts and I've seen that you mostly recommend using google to search for these charts. The problem is that the information provided by various websites seems contradictory. One website says that material X is resistant to chemical Y (considering also the temperature and concentration), another website says the contrary - that material X is in fact severy damaged by chemical Y.

I noticed this while comparing the chemical resistance of PTFE/Teflon reported by these websites:
http://www.jenseninert.com/chemical-resistance.htm
http://www.buerkle.de/eng/d2-1.php (the Excel file)
http://www.coleparmer.com/TechInfo/ChemComp.asp
http://www.efunda.com/DesignStandards/oring/oring_chemical.c...
http://www.zeusinc.com/chem_ptfe.asp

For example, some say PTFE has excellent resistance to Bromine at 50 degr. C, others say it has poor resistance.

Maybe it wasn't such a good idea to use PTFE for the comparison, but the question remains: which chemical resistance chart should I trust? Which one do you trust, when you need such a thing? If you use a book instead of the Internet - which book? Or which source?

I'm interested in the resistance of various materials, not only plastics, and to as many chemicals as possible, so the larger the charts the better.

Thanks in advance for your help. And sorry if I posted my message on the wrong topic board.

unionised - 18-9-2006 at 10:06

"need a trustable and accurate source for chemical resistance charts. "
Sorry, but the only way to be sure is to do the experiment yourself.
Not least because "resistant to bromine" might mean " The stuff pisses through, but the PTFE is OK". If you want a bottle top that isn't resistant.

chromium - 18-9-2006 at 10:22

You probably can not trust any resistance charts. As we have seen here, even best chemistry handbooks contain some errors. Whenever possible do your own tests and use resistance charts as source for ideas.

Another way is to look what materials are commonly used in particular manufacturing (or refining) processes and just use these materials.


[Edited on 18-9-2006 by chromium]

ethan_c - 18-9-2006 at 12:21

In your particular example, suffice to say: If it is organic, bromine will destroy it. If it is a metal, bromine will likely destroy it. If there is any small possibility of the container not being sealed in a manner sufficient for high vacuum, bromine will find that possibility and laugh at you as it exits your holding device.

tjax - 18-9-2006 at 13:02

Thanks for the answers. I agree with you that the only way to be absolutely sure is to do the experiment yourself. But sometimes, to avoid some mistakes, a good chemical resistance chart might be useful (see also http://www.sciencemadness.org/talk/viewthread.php?tid=2529#p... , I found it while browsing the boards)

So I'll rephrase my question: do you know any chemical resistance chart that you consider to be good, based on your experience? One that you noticed has less mistakes than others? One that you first go to when you need such a chart?

matei - 18-9-2006 at 13:20

You can find lots of useful tables in "The Laboratory Companion - A Practical Guide to Materials, Equipment, and Technique" (you can find it on rapidshare).

Magpie - 18-9-2006 at 18:59

As you likely know just because someone publishes a table, either as a book or some narrative on the internet, does not in itself make it trustworthy. You have to examine the reputation and credentials of the author(s). These tables are very useful for screening candidates for material selection. Once you have made a short list of candidates you may want to do some testing, depending on how you are pushing the limits of the material, and the risks involved. I go to Perry's "Chemical Engineer's Handbook" first as it is heavily peer reviewed and has stood the test of time for many decades. I would also think that lists supplied by the major lab suppliers would be reasonably reliable - they have their reputation at stake with all their customers. So you have to evaluate each source on its own merits - just like you would evaluate the opinions of those from whom you seek advice. ;)

Jdurg - 21-9-2006 at 17:52

Quote:
Originally posted by ethan_c
In your particular example, suffice to say: If it is organic, bromine will destroy it. If it is a metal, bromine will likely destroy it. If there is any small possibility of the container not being sealed in a manner sufficient for high vacuum, bromine will find that possibility and laugh at you as it exits your holding device.


Hehe. Bromine is a little bitch. It will also just sit around happily confined until one day it says "You know what? I hate being in this glass tube. I'm going to seep out of it an expand my horizons. Kiss my ass world." :P

The_Davster - 21-9-2006 at 17:56

I keep 5 mls of bromine in my freezer at -30 in a volumetric flask with ground glass stopper wrapped in teflon. I keep some Al foil near it and so far so good!