Effect of hardness on chemical compatibility of HNBR

[gagandeepsidhu]

We use HNBR (Hydrogenated Nitrile Butadiene Rubber) for a bladder cage in seal on our drilling tool. The bladder cage act as oil container for seal. The current recommended hardness spec ask for 85 +/- 5 duro hardness. Vendor is having a hard time in avoiding entrapped air which cause deffects or fracture in rubber. They have recommended that if we can reduce the hardness requirement to 75 +/- 5 duro, it will help in avoiding this issue.

Can someone advise if doing this change will make any diffrence in chemical compatibility or temperature handling abilities of rubber?

 

[berti]

Hi all,

hardness change (of 10 pts) is the variable which I would expect to have very few (if any) influence on chemical and thermal resistance. But take care that the new compound is made from same polymer and by same crosslinking system as your old one, because the type (ACN content and content of unsaturation)and crosslinker is vital for resistance. Your supplier should change only the filler (carbon black ) content, but nothing else.

Hope to help

Berti