New role of ionic liquid as accelerator activator in rubber compounds and its influence on curing and mechanical properties

This study focuses on the effect of ionic liquids (ILs) on the cure characteristics and filler dispersion of natural rubber (NR) and styrene-butadiene rubber (SBR) gum and filled compounds. The complexation of ionic liquid with zinc oxide (ZnO) increases the activity of ZnO and the cure rate together with improved filler dispersion. This has also increased the rubber filler interaction. Imidazolium and chloride based ionic liquids with different cationic groups were compared and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, and differential scanning calorimetry to understand the thermal and chemical behavior of the compounds. Interestingly, it was found that the ionic liquid can act as an activator and is able to accelerate the vulcanization rate with improved rubber filler interaction. The complexes formed by IL-Zn were shown to be much more reactive than Zn-stearic acid complexes. The dispersion of carbon black in the NR and SBR compounds was studied by using Field Emission Scanning Electron Microscope and Transmission Electron Microscope and the results demonstrate that ILs could significantly improve the filler dispersion. Thus, this study has revealed the multifunctional role of ionic liquids in rubber compounds.Highlights This article describes the dual role of the ionic liquid (IL) in rubber compounds. It can act both as an accelerator-activator as well as an efficient dispersing aid. The complexation of IL with zinc oxide (ZnO) plays a crucial role in enhancing the activity of ZnO. As a result, the physico-mechanical properties of both natural rubber and styrene-butadiene rubber based compounds are significantly improved. Interaction of Ionic liquid in rubber compounds in presence of activator and accelerator. image