Tensile strength and elongation at break were measured using
dumbbel type specimens according to ASTM D412. Tensile tests
were carried out on a Hiwa 200 tensometer at 500 mm/min crosshead
speed at room temperature. Hardness tests were carried out
using shore A Durometer according to ASTM D2240. The
percentage of abrasion resistance was measured according to
DIN5356. The test conditions and procedure of compression set
testing followed ASTM D395 Method B (under a constant
deflection in air). Resilience test was carried out using ASTM
D1054, performed by Hiwa 300. The effect of thermal ageing on
the mechanical properties of the NR/SBR blend was studied by
keeping the dumbbel samples in an air oven at 100 1C for 48 h.
The NR/SBR samples were then conditioned at ambient temperature
for 24 h before testing according to ASTM D573. The changes
in tensile strength, elongation at break and hardness before and
after the thermal ageing conditions were then evaluated. Three
samples were tested for each set of experiments.