Nanosized Zinc Oxide Grafted with Ionic Liquids – New Activator for Sulfur Vulcanization of SBR Rubber
Vulcanization is one of the most popular and important processes in rubber industry. Activators are crucial processing additives, which not only activate vulcanization but also improve the efficiency of curing system. The most common activator is metal oxide, such as zinc oxide (ZnO) with fatty acids (stearic, lauric, palmitic and oleic acid). Fatty acids solubilize the zinc cation from ZnO and consequently the actual catalyst is formed. Zinc oxide reduces the vulcanization time and improves physical and thermal properties of rubber compounds. However, according to the Environmental EU legislation, it is required to reduce the amount of ZnO and Zn-containing compounds in rubber technology. The way to do this is the application of nanosized zinc oxide (nZnO) with higher activity in vulcanization than micro-ZnO. Ionic liquids (ILs) can be used to improve the dispersion of nZnO nanoparticles in the elastomer matrix. The first step of this work was to obtain new activating system based on nZnO modified with ILs directly in the elastomer matrix or in the solution process. The second part of this research was to study the effect of this activating system on the vulcanization of styrene-butadiene rubber and properties of vulcanizates. The proposed activating system resulted in improved mechanical properties and resistance to thermo-oxidatve aging of vulcanizates. Moreover, nZnO/ILs system reduced the time and temperature of vulcanization as compared with SBR compounds without addition of ILs.
Keywords - Sulfur vulcanization, SBR, Zinc Oxide, Ionic liquids.