Sciencemadness Discussion Board

Distillating PU from PU paint.

DubaiAmateurRocketry - 8-6-2013 at 10:58

How do i distillate Polyurethane from Polyurethane Varnish ?

On the MSDS it says its dissolved in Naphtha, but i fear PU might decompose before the temperature of naphtha's boiling point ?

ummm ? help ?

kristofvagyok - 8-6-2013 at 11:36

Contrariwise.

The polyurethane will decompose at higher temperatures, but the naphtha could be distilled easily from the solution. Why? How does the paint works? You paint something with it, the naphtha evaporates and the solid PU is left back.

Polymers are usually not distillable, just like in this case. Their high molecular weight and their large chain like structure does not allow them to evaporate, they just degrade, decompose on heating.

DubaiAmateurRocketry - 8-6-2013 at 22:01

Quote: Originally posted by kristofvagyok  
Contrariwise.

The polyurethane will decompose at higher temperatures, but the naphtha could be distilled easily from the solution. Why? How does the paint works? You paint something with it, the naphtha evaporates and the solid PU is left back.

Polymers are usually not distillable, just like in this case. Their high molecular weight and their large chain like structure does not allow them to evaporate, they just degrade, decompose on heating.


It takes too long, if i just open the cap of my paint it will probably take few month, I once poured around few grams of PU paint into a bottle cap, and i had to wait 2 weeks until its completely cured, like are u kidding me, 2 weeks... I guess it needs a high surface area, like how paint works, its really just a thin surface of it so it can dry in a day.. but how do i do it fast in a bottle ? Can i heat the thing to like 100 degree ? without it degrading ?

Fantasma4500 - 9-6-2013 at 02:51

you should first check up on what temperature the polyurethane decomposes at
and secondly you could put it on a stove, knowing that it wont exceed that temperature
i suppose its flammable stuff youre going to decompose
the more heat the more evaporation obviously (:
also a big plate of steel or something might be what you wanna use and put it outside in the sun.. oven pans perhaps? where im from theyre pitch black and that would give quite some heat when its put in direct sun

unionised - 9-6-2013 at 07:02

Quote: Originally posted by Antiswat  
you should first check up on what temperature the polyurethane decomposes at
and secondly you could put it on a stove, knowing that it wont exceed that temperature
i suppose its flammable stuff youre going to decompose
the more heat the more evaporation obviously (:
also a big plate of steel or something might be what you wanna use and put it outside in the sun.. oven pans perhaps? where im from theyre pitch black and that would give quite some heat when its put in direct sun


Don't put flammable things on the stove unless you want a fire.

Finnnicus - 9-6-2013 at 07:10

That's really not true unionised. What about pretty much every organic solvent? Unless you mean an open flame.

Personally I would paint it onto non-stick paper, then let it dry somewhere hot.

unionised - 9-6-2013 at 07:57

I suspect that there are more gas, wood coal or paraffin stoves in the world than electric ones, but even if I'm mistaken it's ill advised without checking.

Incidentally, I'd paint the stuff onto a sheet of glass and then let it dry. With luck you can scrape the PU off with a razor blade.
it's worth dropping a little water onto the edge of the varnish layer- it wets the glass and sometimes lifts the whole polymer film in one piece.

Quite what the point of this exercise is, I'm not sure.
Do you realise that PU paints set because the poly isocyanates in them react with water from the air?


[Edited on 9-6-13 by unionised]

DubaiAmateurRocketry - 9-6-2013 at 10:50

Quote: Originally posted by unionised  
I suspect that there are more gas, wood coal or paraffin stoves in the world than electric ones, but even if I'm mistaken it's ill advised without checking.

Incidentally, I'd paint the stuff onto a sheet of glass and then let it dry. With luck you can scrape the PU off with a razor blade.
it's worth dropping a little water onto the edge of the varnish layer- it wets the glass and sometimes lifts the whole polymer film in one piece.

Quite what the point of this exercise is, I'm not sure.
Do you realise that PU paints set because the poly isocyanates in them react with water from the air?


[Edited on 9-6-13 by unionised]



Ummm wtf ? so the thing we buy only has Isocyanates ? you must be kidding me ? So i can just add for example sugar or alcohol that has OH in it to simply bond with it umm ?

unionised - 10-6-2013 at 04:05

At least some of the "polyurethane" varnishes I have seen contain isocyanates. Generally so call pre-polymers.

What are you actually trying to do?

DubaiAmateurRocketry - 10-6-2013 at 10:27

Quote: Originally posted by unionised  
At least some of the "polyurethane" varnishes I have seen contain isocyanates. Generally so call pre-polymers.

What are you actually trying to do?


Using as fuel. Can i know where you got your information please ? and do you know which types of Isocyanate and brands has it ?

I will try to heat my PU varnish for 1 hours at 100 degree, or 80, and, add some Sucrose, alcohol to see if it solidify, if it has extra isocyanates it shall.

Fantasma4500 - 11-6-2013 at 07:09

dont hang me up on this, but im quite sure ive seen some pressure bottle shoot out some yellow stuff that expands and hardens up..

''PU foam'' and im 70% sure i checked on it that it did 'contain' polyurethane
this should be possible to get pretty much anywhere..

anyways why dont you upload your results or link to them on this thread if you manage to use it as a fuel? sounds interesting as always

DubaiAmateurRocketry - 11-6-2013 at 07:23

Quote: Originally posted by Antiswat  
dont hang me up on this, but im quite sure ive seen some pressure bottle shoot out some yellow stuff that expands and hardens up..

''PU foam'' and im 70% sure i checked on it that it did 'contain' polyurethane
this should be possible to get pretty much anywhere..

anyways why dont you upload your results or link to them on this thread if you manage to use it as a fuel? sounds interesting as always


k, I will, Ill mix it with some alcohol, sugar soon. and see if it solidify.