RobT - 21-1-2013 at 13:45
Hi,
How resistant is cork to hydrochloric and glacial acetic acid vapours over long periods of time (~24 hours)? If it isn't then does anyone know where I
can get wide (at least 10cm HDPE or PTFE bungs?)
Thanks,
Rob
12AX7 - 21-1-2013 at 16:23
Just for 24 hours wouldn't be a problem, but it's not a permanent solution by any means, and it's not like the seal is very good. You'll easily smell
the vapors through it.
Over a period of days to weeks, I think, acids hydrolyze cellulose (which I assume is the main component of cork). Which will darken, dissolve and
destroy it. GAA may dissolve it (think rayon), but then again, that's cellulose acetate, isn't it? Which requires acetic anhydride to
produce; no danger of that here.
Tim
woelen - 22-1-2013 at 04:36
I would not use cork at all for such situations. It contaminates your liquids. Cork gives off yellow/brown stuff, especially when wet and strongly
acidic. This may leak into your liquids. Try to find rubber stoppers, you can find them on eBay in many different sizes and they are cheap. Rubber
stoppers are no permanent solution for storage, but they are quite useful for experimental setups, where a glass opening must be sealed for a limited
amount of time. A little glass tube or plastic tube also can be punched through the rubber stopper.
I have done experiments where I used rubber stoppers, even in chlorine generators. They withstand the chlorine for hours at least and provide a
perfect seal.
plante1999 - 22-1-2013 at 05:42
Cork can be really useful when impregnated with sodium silicate solution and dried. They make a substitute for ground glass apparatus in some cases. I
don't remember where I read it tough.
[Edited on 22-1-2013 by plante1999]
Endimion17 - 22-1-2013 at 06:05
Plante, that's true, but they do become stiff and break quite easy. Also, it couldn't withstand hydrochloric acid mist for a whole day.
The solution is to wrap the hell out of them using PTFE tape (at least that's cheap). I mean to really, really wrap them good. That way, they hold up
for a few days below room temperature. Later they become yellow and soft.
Natural rubber also hydrolizes and gives coloured products but it takes a few days in warm conditions.