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 RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
