Abstract. Pyrolytic carbon black (CBp) and pyrolytic oil (Op) made from used tires were used in natural rubber (NR)/
styrene-butadiene rubber (SBR) blends. The effects of CBp and Op on the processing properties, the mechanical properties
and the dynamic mechanical properties of the NR/SBR blends were investigated and compared with a control sample that
was prepared with N550 and commercial process oil. It was found that the effect of CBp on the processing properties of the
NR/SBR blends was similar to that of N550. With the increase of the CBp content, the curing properties of the NR/SBR
blends changed little. The reinforcing effect of CBp was inferior to that of N550. With the increase of the CBp content, the
tensile strength, tear strength and modulus at 100% elongation of the NR/SBR vulcanizates decreased significantly.
Dynamic mechanical properties of the NR/SBR blends were also affected and all samples comprising CBp have a higher
tan ! than control sample. It is suggested that the low surface area and high ash content of CBp strongly effects all of these
property changes of the NR/SBR blends. The morphology and distribution of the carbon black particles are studied using a
scanning electron microscope. It was also found that with the increase of the Op content, the properties of the NR/SBR
blends were strongly affected due to the high sulfur content of Op, which produced a high crosslinking density.