ZnO particles in un-valcunised NBR
ZnO particles in un-valcunised NBR
(OP)
Hi
In unvulacnised form, when I section cut NBR, I see some white particles under 20X magnification.
Got it tested and found to be ZnO. Supplier say it's normal.
Anyway to prevent? What could be likely cause?
Thanks much for reading.
In unvulacnised form, when I section cut NBR, I see some white particles under 20X magnification.
Got it tested and found to be ZnO. Supplier say it's normal.
Anyway to prevent? What could be likely cause?
Thanks much for reading.





RE: ZnO particles in un-valcunised NBR
You could test the dispersion in your vulcanised article. If it is too low, then you can go to your supplier and ask for improvements.
RE: ZnO particles in un-valcunised NBR
I have encountered maldispersion of zinc oxide in my standards work although not specifically with NBR. It is important to add the activator early in the mixing cycle, with or without fillers, and certainly before the stearic acid and plasticizers or oils. Ensure the zinc oxide is dry and avoid old stocks. I agree with Metten about masterbatches: some using NBR as the binder are commercially available. Coated grades are also around. As regards particle size I am unsure about active zinc oxide - some people say it disperses more easily than normal grades, others the reverse. One advantage is that a lower level can be used.