The compression set value was determined using a compression device consisting of two or more flat steel plates between which the foam specimens were compressed. The test specimens were compressed to 50% of their original thickness and the compression device was placed in the oven at 70ºC for 72 h. At the end of the test period, the specimens were removed, and the thickness was measured after 30 min rest at room temperature. The compression set percentage was then calculated.
The foam samples that underwent the indention test were then placed in a heated air oven and aged for 22 h at 100ºC. After the exposure period, the oven was opened and the samples were removed immediately. The samples were allowed to cool to room temperature for not less than 16 h before the final indentation hardness value was determined. The age hardening percentage was then calculated.