Rheological behavior on various mixing times for natural rubber/nano carbon black composites

Natural rubber (NR) can be reinforced using nano carbon black (NCB). Such composite is usually provided as a master batch for raw materials used in tire industries. This paper reports the rheological behavior of NR/NCB composites prepared using an internal mixer. Rheological behavior was investigated from the value of the Mooney viscosity at 100°C which was conducted according to ASTM D1646-04. The effect of mixing times (10, 12, and 14 minutes) at a fill factor of 83%, and 6 months of storage time on the rheological behavior of the NR/NCB were studied. The result indicates that the Mooney viscosity of the NR/NCB composites decreased by more than 25% along with mixing time. The decreasing behavior was explained by the size reduction of agglomerates and the distribution of NCB. Mixing NR/NCB in a high-fill factor gives high shearing force to the composites that influence viscosity. Subsequently, a storage time of 6 months also reduces the viscosity of the NR/NCB composites.