Cure Characteristics and Physico-mechanical Properties of the Stearic Acid Surface of Modified Calcium Carbonate Reinforcement NR/SBR Compounds

Calcium carbonate is a cheap and readily available filler used in rubber industry. This material is not compatible with rubber matrix, so many researchers have tried to modify its surface with various materials in order to increase its hydrophobicity and improve compatibility with the rubber matrix. In this effort, surface modification of calcium carbonate was carried out by 1.5%, 3% and 4% stearic acid to achieve the technical knowledge of preparation method. The surface adjustments were investigated by Fourier transform infrared spectroscopy (FTIR), thermal analysis (TA), and scanning electron microscopy (SEM) and were compared with imported surface modified calcium carbonate (ISMCC) used in the rubber industry. Results showed surface modifications have been accomplished successfully. Furthermore, efficiencies of the prepared surface modified calcium carbonates (SMCCs) were investigated as fillers in the NR/SBR-based compounds. Cure characteristics and physico-mechanical properties of the compounds were considered and compared with reference compound that contained ISMCC. Using calcium carbonate modified by 3% stearic acid as a filler (SMCC(2)) not only preserved compound properties but also improved tensile properties, shortened the cure time and improved aging resistance in comparison with ISMCC.