Preparation of Pyrolytic Carbon Black from Scrap Tire Rubber Crumb and Evaluation in New Rubber Compounds

Summary: Pyrolytic carbon black (CBp) has been prepared by rubber crumb pyrolysis under nitrogen flow at 700 °C. The CBp obtained by this process had an average surface area of 81 m² · g^?1 and was obtained in 43% yield over the starting rubber crumb. Although the CBp surface area can be increased up to 109 m² · g^?1 by washing away the Zn‐ and Si‐based ashes with HF treatment, the CBp was tested in a standard NR/SBR‐based formulation without any purification and ash extraction. CBp was tested at increasing loading levels as partial or full replacement of a standard N339 furnace carbon black. CBp depresses the physical properties of the rubber compound in a way which is directly proportional to the amount added. The reason of this result and the limited reinforcing effect is discussed in terms of low surface area and low structure in comparison to N339 carbon black as well as in terms of low surface activity, the interference of the ashes and the poor dispersion. Ideas of further development works are outlined.