Air trap in epdm rubber compound

[nightrain]

Hi guys,

Currently i am having a problem with my epdm compound formula, the problem is that there are many air traps / blisters on the surface of the calendared blank sheet.

Here are the formula below:
Vistalon 7001 100 phr

Clays 325 mesh 140 phr
Calcium carbonate 400 mesh 230 phr

N-330 Carbon black 30 phr
Parrafinic oil 30 phi

I have also tried to put 5 phr of calcium oxide but it didn't work... any suggestions ? thanks before

 

[tom1953]

It seems like the compound would be very 'dry', with 400 phr of filler and only 30 phr of plasticizer. Is this a formula that Exxon recommended? Is there more to the formula than what you show? Maybe some process aids would help. I'd consult with your EPDM supplier for their suggestions.

Good Luck!

 

[GrahamBennett]

I agree with Tom, your compound does seem to be very dry. Also, what gauge are you calendering at?