INFLUENCE OF STORAGE TEMPERATURE AND TIME ON MOONEY VISCOSITY AND BOUND RUBBER FORMATION IN NATURAL RUBBER COMPOUNDS FILLED WITH CARBON BLACK AND LOCAL SILICA

Aging experiments were carried out on natural rubber compound filled with both carbon black and silica.  The type of silica employed in this research was local silica. Silica loading was 0, 5, 10, 15 and 20 phr, and carbon black was set to be fixed. The samples were subjected to thermooxidative aging at temperatures mainly at 40 o C, 45 o C, 50 o C, 55 o C,  and 60 o C. The samples were taken out everyday up to four days storage time to investigate Mooney viscosity and bound rubber. In this study, Mooney viscosity increases with increased storage temperature and storage time. The storage temperature at 60 0 C gives an extreme effect on Mooney viscosity of uncured rubber compounds so the measurement cannot be performed. Bound rubber decreases with increased silica content, and the storage temperature and time do not significantly affect the bound rubber content. Keywords: natural rubber compound , carbon black , silica , mooney viscosity , bound rubber