Effect of bis[3-(triethoxysilyl)propyl] tetrasulfide, polyethylene glycol and polypropylene glycol on the behavior of silica filled rubber compounds based on natural rubber

The aim of this work is study to the influence of common silane coupling agent Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) on dispersibility of highly polar silica particles in non-polar Natural Rubber (NR) based compounds and correlate the results with possible alternative additives from the group of polyethers, Polyethylene Glycol (PEG) and Polypropylene Glycol (PPG). For that purpose, uncured and cured rubber compounds with different dosage of TESPT, PEG and PPG have been prepared and investigated. The Rubber Process Analyzer (RPA) has been used to quantifying the changes in microstructure interaction of uncured rubber compounds. Effect of presence of dispersant additives on mechanical properties has been investigated in cured rubber due to tensile analyses. Finally, the degree of silica particles dispersion in rubber matrix has been monitored by a reflected light microscope DisperGRADER. It has been found, that addition of chosen dispersant additives leads to improve of dispersion of silica particles in rubber matrix resulting in betterment of mechanical properties. It was confirmed that silane coupling agent creates more durable chemical bonds, which affect mechanical properties more than physical hydrogen bonds in case of polyethers. From RPA measurement, it is evident that rubber compounds containing silane exhibit more stable enhance of mechanical properties.