The medium temperature pyrolysis process using a fixed-bed reactor at atmospheric pressure was utilised to recover carbon black from motorcycle and automobile tyres. Experimental results have shown that the ash and volatile contents of several recovered carbon blacks are high, the elongation at break of the vulcanised natural rubber filled with recovered carbon blacks from motorcycle tyres is better than that from motorcycle tyres and standard carbon black 7#, while the other mechanical properties are worse. In order to improve the reinforcing effect of recovered carbon blacks, the modification of recovered carbon black was performed by high-energy electron bombardment and non-oxidising acid. The specific surface area of the pyrolytic carbon blacks increased after high-energy electron bombardment. The ash content of the pyrolytic carbon black was reduced from 22.5% to 8.4% after rinsing with hydrochloric acid, and the tensile stress at 300% was increased by about 2.2 MPa.
Keywords: Waste tyre; carbon black; chemical modification; mechanical properties; pyrolysis; recovery.