Resin/Hardener Air Absorption and Storing under Vacuum

[esteess]

I have couple of questions with regards to degassing/storing the epoxy resin (toughened) and hardener (anhydride).

1. Is the any harm to both of the above if I keep them in separated vacuum chambers, isolated and under vacuum pressure instead of original container in the room temperature and atmospheric pressure?

2. If I was to degas both, resin and hardener separately and let the atmospheric pressure into the chamber and keep inside them instead of original container (isolated) is the a chance for the air to go back into each of components if they are not being disturbed/exposed to the moisture and if so after what time approximately?

Regards,
Stan

 

[berkshire]

If you let atmospheric air go back into the chambers , it will carry in moisture and CO2.Depending upon the hardener you are using , you may get adverse results. You would be better off using an inert gas.
B.E.

You are judged not by what you know, but by what you can do.

 

[Compositepro]

Flushing the head space of storage containers with nitrogen after opening is a fairly common procedure. Vacuum is rarely used for storage because it requires vacuum rated vessels, and avoiding vacuum leaks is difficult. Many resins will slowly react and degrade with exposure to oxygen or moisture.

 

[esteess]

Compositepro,

Thanks for the suggestions.
I agree on your statement regarding degradation and moisture absorption, however the amount of the air in the container is driven by the volumetric space of it, because it is sealed.
Wouldn't this be exact replication of the normal storage of compound i.e. in the sealed drum? Every time you open drum and take some resin out, then put the lid on you entrap air inside the drum.

 

[Compositepro]

I'm not sure what you are asking. Full drums contain little head space so flushing with nitrogen is less important at initial fill. After the drum has been opened several times the head space becomes a significant volume and air is introduced with every opening, so nitrogen flushing becomes important. Also, completely sealing the drum after a while becomes less reliable. Even a tiny leak will allow the drum to breathe due to temperature cycles. To be clear, nitrogen flushing is done just prior to resealing a drum. It is not a continuous flush, although I suppose, it could be.

 

[berkshire]

esteess,
You might want to look at Composite pros reply on thread332-355779 It covers much of the same ground you are asking .
B.E.

You are judged not by what you know, but by what you can do.