Various Ways to Reduce Zinc Oxide Levels in S‐SBR Rubber Compounds

Abstract

Abstract Because of environmental concerns, the zinc content in rubber compounds has come under scrutiny. The research described in this article encompasses zinc‐oxide, various zinc‐complexes and alternative metal oxides as activators for sulphur vulcanisation. Regarding zinc complexes, it can be concluded that zinc‐ m‐glycerolate is a good substitute for ZnO as activator for sulphur vulcanisation in s‐SBR rubber, without detrimental effects on the cure characteristics. Of particular interest is also the positive effect of CaO and MgO in s‐SBR, while BaO, Cu(II)O and BeO hardly show any activation. The present article also reports on the application of a novel activator for sulphur vulcanisation: ZnClay. Results with s‐SBR rubber demonstrate, that this ZnClay can substitute conventional ZnO, retaining the curing and physical properties of the rubber products, while significantly reducing the environmental impact. A reduction of the zinc concentration with a factor 10 to 20 can be realised. Model Compound Vulcanisation studies are used to gain insight into the mechanism of this activator.