Cure characteristics and physicomechanical properties of calcium carbonate,
CaCO3, reinforced rubbers (NR, NBR) were studied. Minimum torque, maximumminimum
torque, cure rate and the scorch and cure time of the prepared rubber
compounds were assessed by using a Monsanto Oscillating Disc Rheometer (ODR-
100). Stress and strain at yield and at rupture before and after aging were determined
by using a Zwick tensile testing machine (Model 1425). Results showed that cure time,
cure rate index (CRI), maximum torque, stress and strain at yield demonstrated clearly
the optimum filler content for each type of rubber. Values of the rubber-filler
interaction parameter (m) were 0.585 and 0.175 for NR and NBR respectively and
suggested good NR-filler interaction than that of NBR where the dilution effect of NBR
becomes more significant as the filler loading is increased. The aging behavior
(resistance to deterioration) of the prepared rubber compounds due to the prolonged
exposure of γ-irradiation was estimated by plotting the percent-retained values of the
physicomechanical properties at different γ-doses.