The present study examines the effects of carbon nanotubes (CNTs), 3-aminopropyltriethoxysilane (APTES)-functionalized CNTs (sCNTs), bis(triethoxysilylpropyl) tetrasulfide (TESPT)-functionalized CNTs (tCNTs), and 1-octadecanol-functionalized CNTs (cCNTs) on the rheometric behavior, mechanical properties, morphology, abrasion resistance, swelling resistance, compression set, and crosslinking density of ethylene-propylene-diene monomer/styrene-butadiene rubber (EPDM/SBR) composites. The filler content was varied from 0 to 8 phr (parts per hundred rubber). In terms of rheometric behavior, properties such as minimum torque, maximum torque, delta torque, and cure rate index increased with higher filler content, while scorch time and optimum cure time decreased. Regardless of the filler type, increasing the filler content led to higher compound viscosity, reduced cure time, enhanced crosslink density, and improved abrasion resistance and hardness of the vulcanizates. For all filler types, tear strength, compression set, and swelling resistance showed a consistent increase with rising filler content. However, tensile strength increased with filler content up to 5 phr but declined noticeably beyond this threshold for all filler types. At any given filler content, CNTs demonstrated superior compression set performance compared to sCNTs, tCNTs, and cCNTs.
