2.3. Mechanical property measurement
The hardness was measured using a Wallace Shore A durometer, according to ISO 7619-1. Compression molded sheets having a thickness of about 1.2 mm were used for tear and tensile testing. Tear and tensile properties of the specimens were measured following ISO 34-1 and ISO 37, respectively. Crescent test pieces were used for determining the tear strength. The measurements were carried out using an Instron Universal Tester (Model 4301) with a crosshead speed of 500 mm/min and initial clamp separation of 65 mm. The values of tear and tensile properties were the average of 4–5 specimens.
The heat build-up and crack growth resistance of the vulcanizates were measured, in accordance with ISO 4666 and ISO 132 using Goodrich flexometer and De Mattia type machines, respectively. Dynamic compression set was evaluated using the same specimens as for heat build-up testing. The original height of the specimen was measured prior to heat build-up testing and the specimen was left at 25 °C for 1 h after the heat build-up test. Thereafter, its final height was measured and the compression set was calculated using the following equation.