EPDM

[cjrmaterials]

Hi All,

I have been testing a peroxide cured EPDM material as a o-ring seal in a high humidity environment. I'm finding leaks in some materials aged at temperatures of 40 degrees C. I've had a look at these samples with SEM and can see cracking on the surface of failed samples and using DSC have seen an exotherm at ~180 degrees C in same samples. I have also noticed significant drops in creep resistance under compression.

~I figured perhaps I wasn't curing the material correctly, but cant find any evidence of an exotherm straght after curing.

Has anyone experience of EPDM degradation at high humidity/temps of 40 degreeC
Thanks,

 

[btrueblood]

No, and it's usually a very stable, high set-resistant material, as compared to a sulfur cured version. Is there any chance that there is some hydrocarbon (oil, grease, wax) contaminant getting onto the seals?

 

[cjrmaterials]

Ya that's what i was thinking. No I can't find any evidence of contamination.

 

[btrueblood]

I think the 180C exotherm is the evidence...the question is more: what possible source of hydrocarbons, solvents, etc. could be causing it? Think both liquids and vapors.

FWIW, I had a long struggle with a new EPDM diaphragm seal degradation in hot water testing. We never really found the source, but worked hard to fully clean and degrease the test system piping, and to eliminate things like bladder tanks with butyl rubber seals, eventually the problem "dried up".