Cure Properties of the Rubber Compounds The scorch time (ts1Þ, which is the time for the onset of cure, and the optimum cure time (t90Þ, which is the time for the completion of cure, were determined from the cure traces generated at 16062C, using an oscillating disc rheometer curemeter (ODR, SANTAM SRT-200B, Santam Company) at an angular displacement of 63 and a test frequency of 1.7 Hz. These tests ran for up to 18 min. DTorque, which is the difference between the maximum and minimum torque values on the cure trace of the rubber and which is an indication of CLD changes in the rubber, was also determined from the cure traces. Figure 2 shows typical cure traces produced in the ODR. The cure rate index (CRI), which is a measure of the rate of curing in the rubber, was calculated using