where q is the rebound angle and 45 is the initial angle.
Heat build-up and compression set were determined
using a Goodrich flexometer (model II). The vulcanized
specimens were tested at 100 C to determine the
temperature rise, in accordance with ISO 4666. Thereafter,
the tested specimens were stored at room temperature for
1 h before measuring their final height. The compression
set value was calculated using Eq.