Effect of Silicon Carbide on the Properties of Natural Rubber Blends with EPDM Rubber

Rubber composites are used in many applications such as the rubber O -ring in solid oxide fuel cell unit. O-ring is used to separate hydrogen and oxygen and it must withstand heat in the range of 600 - 1,000 degrees C. To improve thermal properties of O- ring rubber, silicon carbide (SiC) was applied to rubber owing to the high thermal stability and good oxidation and corrosion resistances. Blends of natural rubber/ ethylene propylene diene monomer (NR/EPDM) were prepared in an internal mixer. The semi-EV of Sulphur was used. The effect of the silicon carbide level (5, 10, 15, and 20 phr) on the cure characteristic, mechanical, thermal and morphology properties of silicon carbide filled 30:70 NR/EPDM were studied. The curing properties show that the tc(90) and tS(2) of NR/EPDM blends increased with the increasing SiC loading. The effect of SiC loading on the tensile strength of NR/EPDM blends showed that tensile of vulcanizates increased with the increasing SiC up until 10 phr, extra addition of SiC would deteriorate the tensile properties. The thermal oxidative property of SiC filled NR/EPDM were satisfactory at all SiC loadings.