The properties of ethylene-propylene elastomers obtained with the use of a new cross-linking substance

In this work, the effect of a new filler on cross-linking of ethylene-propylene rubber (EPM) was investigated. A filler with a core-shell structure ZnO/SiO2 (precipitated silica modified with zinc oxide) was introduced into rubber compounds. It was proved using of those substance to cross-link EPM caused the formation of labile ionic clusters in elastomer network. These non-covalent cross-links were generated due to interactions occurring between metal ions and functional groups of rubber (namely carboxyl groups) introduced via rubber functionalization with maleic and itaconic acids derivatives. The optimal curing time of rubber compounds was investigated. The cross-link density of the vulcanizates obtained was studied by equilibrium swelling in solvents (e.g., toluene). Additionally, the results confirmed that vulcanizates received using modified silica contained specific cross-links disintegrating under ammonia vapors. Physical relaxation at ambient temperature confirmed the influence of non-covalent cross-links on stress dissipation in the vulcanizate. The static and dynamic mechanical properties of vulcanizates obtained were also determined.