The role of the activator during the vulcanization of natural rubber using sulfenamide accelerator type

In this work the role of Zinc Oxide on each one of the three steps of CBS accelerated vulcanization process of natural rubber (intermediates formation, cross-link formation and reversion), is studied. For that, the Model Compound Vulcanization (MCV) approach is used and squalene is chosen as model of Natural Rubber. The amount of zinc oxide is necessary for an acceptable reaction rate and a good reticulation is optimized. Other oxides (MgO, CaO and CdO) are compared as possible activators of the vulcanization process and it was observed a different comportment on each case, which makes possible to obtain conclusions about the reaction mechanism. It should be noted the excellent behavior of MgO as activator in the intermediates formation.