The
vulcanization of rubber is a chemical process to improve the
mechanical properties by cross-linking unsaturated polymer chains.
Zinc oxide (ZnO) acts as an activator, boosting the rubbers’
sulfur vulcanization. Maintaining the level of ZnO content in the
rubber compounds as low as possible is desirable, not only for economic
reasons but also to reduce the environmental footprint of the process.
In this contribution, octylamine (OA) capped ZnO nanoparticles (5
nm diameter), prepared through a thermal decomposition method, were
demonstrated to be efficient activators for the sulfur vulcanization
of natural rubber, enabling the reduction of the required amount of
ZnO as compared to commercial systems. The effect of different ZnO
activators (OA capped ZnO/commercial indirect process ZnO) on the
curing characteristics, cross-linking densities, and mechanical performance,
as well as the thermal behavior of rubber compounds, were investigated.
Compared to the commercial indirect process ZnO, OA capped ZnO nanoparticles
not only effectively enhanced the curing efficiency of natural rubber
but also improved the mechanical performance of the composites after
vulcanization. This was interpreted
as, by applying the OA capped ZnO nanoparticles, the ZnO levels in
rubber compounding were significantly reduced under the industrial
vulcanization condition (151 °C, 30 min).