Investigation of the effects of pyrolytic products made from used tires on the properties of rubber blends

In this study, the pyrolytic carbon black (CBp) and pyrolytic oil (Op) made from used tires were used in natural rubber (NR)/styrene-butadiene rubber (SBR) blends and the properties of rubber blends were investigated. The properties and the microstructure of CBp and the properties Op were characterized. NR/SBR vulcanizates were prepared seperately from increasing loading levels of CBp and Op as partial or full replacement of commercial carbon black (N550) and commercial process oil (Octobus N821). The effects of CBp and Op on the processing properties of NR/SBR compounds and the mechanical properties of NR/SBR vulcanizates were investigated and compared with a control sample that was prepared with N550 and Octobus N821. With the increase of the CBp content, while the curing properties of the NR/SBR blends changed little, mechanical properties of the NR/SBR blends were strongly effected. The pyrolytic carbon black was characterized, and the surface area of CBp was found to be lower and the ash content higher than that of commercial oil. It is suggested that the low surface area and high ash content of CBp strongly effects the reinforcing properties of CBp. It was found that, the NR/SBR vulcanizates with increasing CBp content have lower mechanical properties compared with the commercial CB due to the high ash content and low surface area of the pyrolytic carbon black. The distribution of the carbon black particles are studied using a scanning electron microscope (SEM). 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.