ABSTRACT
Glycidyl methacrylate (GMA) was grafted onto styrene-butadiene rubber (SBR) and silica by solution grafting process. Successful grafting onto rubber and silica was confirmed by Fourier-transform infrared (FTIR) spectra, when the peaks at 1149, 842, and 1729 cm-1 attributed to the C-O stretching, the epoxy group, and the C=O stretching vibration of the GMA monomer respectively were followed. After grafting onto the silica surface, the peak at 842 cm-1 in the spectra disappeared which confirmed the grafting reaction through the epoxy group. Grafting onto SBR was also confirmed by proton nuclear magnetic resonance (NMR) spectroscopy and SBR-GMA interaction was shown using two-dimensional proton NMR spectroscopy. The grafted products were further characterized by thermogravimetric analysis (TGA) and differencial scanning calorimetry. Grafting density and grafting weight percentage of GMA grafted silica was calculated using TGA. 10 and 20 percent GMA grafted SBR and 20 percent GMA grafted silica compounds and their vulcanizates were prepared. Rubber-silica interaction through grafted GMA was shown using FTIR spectroscopy, for both types of vulcanizates. Dispersion of pristine and GMA modified silica onto the SBR matrix was quantified using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Mechanical and dynamic mechanical properties of these GMA-modified vulcanizates were studied and compared with previously reported 3-Octanoylthio-1-propyltriethoxysilane (OTPES) modified vulcanizates. Effect of the state of dispersion of silica onto the physico-mechanical properties of the vulcanizates was investigated. The properties of the non-silane modified systems were comparable with and in some cases superior to that of the new mercapto silane-modified systems in the energy-efficient tire application.