Abstract

In a mixed crosslink system (sulfur and metal carboxylate) of XNBR vulcanizate, the variations of the proportions of curatives (low sulfur/high accelerator or high sulfur/low accelerator) have little effect on the vulcanizate properties. But aging studies indicate that the metal ion crosslinks are modified in the presence of a sulfur vulcanizing system. NBR vulcanizates with a comparable recipe have less crosslink density than the corresponding XNBR ones. In general, the technical properties and aging resistance of mixed crosslink systems using ZnO₂ and sulfur donor-sulfur are better than the NBR vulcanizates. Increase of curing temperature does not always lower the technical properties of XNBR and NBR vulcanizates. Addition of XNBR to NBR in XNBR-NBR blends lowers most of the technical properties, possibly due to different vulcanization characteristics.