Mechanical Properties, Set and Rebound Resilience Characteristics of Natural Rubber/Ethylene Vinyl Acetate Blend on Various Ratios

Abstract In this study, natural rubber/ethylene vinyl acetate (NR/EVA) blends are formulated by simple blend using two roll mill. The set properties, both compression and tension, are evaluated as a function of NR/EVA ratios. The ratio of NR/EVA ranges from 100/0 to 95/5, 90/10, 85/15, and to 80/20. Compression and tension set are performed on vulcanized rubber samples at ambient and elevated temperature (100 °C) with constant compression or elongation at 25% of initial value. All tests are carried out for 72 h. Air‐circulated oven is used to conduct testing at elevated temperature. Crosslink density before and after testing is also monitored by equilibrium swelling method. Tensile properties and hardness are also measured to support the discussion. The results show that compression and tension set at ambient temperature tend to increase upon the EVA concentration in the formulation. Set properties are independent of EVA concentration at elevated temperature. Incorporation of EVA decreases the rebound resilience property and thermal aging tends to increase it. The rebound resilience ranges from 31% to 40% for original samples, and from 33% to 43% for aged samples.