Like I said, I'm no chemist. Thanks for straightening all of out Jim. Now
back to our regularly scheduled program. gv
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Friday, August 25, 2006 4:08 PM
To: soaring@airage.com
Subject: [RCSE] Epoxy Odors
Sorry to disagree with you George, but you're wrong. Almost all epoxy
systems consist of two parts. One is the epoxy resin, the clear, gooey,
essentially odorless component. This piece contains epoxide linkages at
each end of each moledule which are just waiting for something to interact
with them. The other part, the catalyst, is a diamine, which is a
compound with a reactive functional group at each end of each molecule.
This is the component that stinks, and will turn yellow with age. Since it
is a diamine, it will interact with water (you can wash the catalyst
container, and yourself with soap and water, unlike the resin). The diamine
is also a sensitizer to both the skin and lungs, and the reason some people
develop allergic reactions to epoxy systems.
Here is a little test you can do yourself. Take a few drops of the catalyst
and place it in a few mL of water. It will disolve. If you try the same
thing with the epoxy resin, it will just sit there. The resin requires an
organic solvent (like isopropyl alcohol or acetone) to disolve, while the
catalyst has both water soluble and organic soluble regions.
The strong odor emanating from the epoxy system that started this thread
suggests that the diamine catalyst is old, or has broken down somewhat.
This tells me that the cured epoxy matrix that will result will not be as
strong as if the components were fresh, since the chain lengths of the
polymer (yes, that is what epoxy is) will be more varied than if the fresh
components had polymerized.
Hope this helps.
Jim Thomas, Ph.D. Organic Chemistry, 1979
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