Physico-mechanical properties of rubber seed shell carbon: Filled natural rubber compounds

Samples of rubber seed shells were carbonized at varying temperatures (100, 200, 300, 400, 500, 600, 700, 800?C) for three hours each and sieved through 150?m screen. The portion of the rubber seed shell carbon that passed through the screen was characterized in terms of loss on ignition, surface area, moisture content, pH, bulk density, and metal content and used in compounding natural rubber. The characterization shows that the pH, conductivity, loss on ignition and the surface area increases as the heating temperature increases, unlike the bulk density which decreases. The compound mixes were cured using efficient vulcanization system. Cure characteristics and physico-mechanical properties of the vulcanisates were measured as a function of filler loading along with that of N330 carbon-black filled natural rubber vulcanisate. The results of the cure characteristics showed that the cure times, scorch times and the torque gradually increased, with increasing filler content for rubber seed shell carbon-filled natural rubber, with filler obtained at carbonizing temperature of 600?C tending to show optimum cure indices. The physico-mechanical properties of the vulcanisates increase with filler loading. The reinforcing potential of the carbonized rubber seed shell carbon was found to increase markedly for the filler obtained at the temperature range 500-600?C and then decrease with further increase in temperature.