Preparation of natural rubber (NR)/ethylene-propylene-diene terpolymer (EPDM) blends by radiation crosslinking and its heat resistance to air aging

To improve the compatibility of natural rubber (NR) and ethylene-propylene-diene terpolymer (EPDM) and enhance the resistance of NR/EPDM blends to hot air aging, radiation-vulcanized NR/EPDM blends were prepared by γ-ray radiation. The effects of blend ratio and radiation vulcanization on the mechanical properties of the blends were investigated by using a uniaxial tensile test. With increasing EPDM content, the tensile strength and elongation at break of the hot-vulcanized sample first decreased and then increased due to the poor compatibility between NR and EPDM. In addition, the mechanical properties of the radiation-vulcanized sample degraded with increasing blend ratio of EPDM. The irradiation treatment improved the initial mechanical properties of the NR/EPDM rubber, and radiation crosslinking enhanced the coupling structure between the NR and EPDM polymer. Following aging treatment in hot air, the mechanical properties of the radiation-vulcanized sample were found to be less degraded than those of the