Cure systems for Low Compression Set in NR

[Pete51]

Of the cure systems listed below, which would likely yield the best (lowest) compression set in a Natural Rubber compound? Also, recommendations on a better one would be appreciated.

TMTM 0.5 phr
Sulfur 0.6 phr
TBBS 1.3 phr
DTDM 0.8 phr

or

CBS 1.75 phr
TMTD 0.3 phr
Sulfur 1.5 phr

The cure system cannot contribute to bloom. Any thoughts, ideas would be appreciated

Thanks,

Pete

 

[GrahamBennett]

Both would give you a compression set value in the region of 10-20% according to the info I have to hand, but I suggest both would fall foul of nitrosamine regulations. Your first suggestion contains TMTM which has been banned in Europe for many years as a nitrosamine generator. Your second contains CBS, which was under consideration as a possible carcinogen.

For the best compression set values you need a cure system that gives a very high proportion of monosulfidic crosslinks, i.e. crosslinks that contain only one sulfur atom (C-S-C) so, I suggest something approaching the following:

Sulfur: 0.60 phr
TBzTD: 0.75 phr
TBBS: 1.50 phr

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[Pete51]

Thank you Graham! How about a replacement of TMTD by TETD?

Pete

 

[GrahamBennett]

I can't say for sure. I suggest you contact your supplier and ask about TETD. In any case, you should be wearing suitable protective clothing, gloves, goggles, and mask when handling accelerators.

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