Properties of Natural Rubber Reinforced by Carbon Black-based Hybrid Fillers

Properties of natural rubber (NR) filled with hybrid fillers were compared. Loading of the primary filler, carbon black (CB), was fixed whereas that of the secondary fillers, carbon nanotube (CNT) and conductive carbon black (CCB), was varied. The increase of secondary filler loading results in loss of elasticity but the increases of viscosity, vulcanization rate, cross-link density, hardness, modulus, thermal and electrical conductivities and tan delta. Obviously, CNT gives stronger effect than CCB. However, CCB gives improvement in tensile and tear strengths when added up to 3 phr whereas the addition of CNT shows no significant effect on the strengths.