PHYSICOCHEMICAL PROPERTIES OF CARBON-BLACKS FROM VACUUM PYROLYSIS OF USED TIRES

Vacuum pyrolysis is a promising way to recover useful products from us ed tires. The two main products from this thermal decomposition proces s are oil and carbon black. In this work the pyrolytic carbon black ob tained under different temperature and pressure conditions was charact erized. The carbon black samples were obtained from pyrolysis of used tires in a batch reactor at temperatures from 350 to 700-degrees-C and total pressures from 0.3 to 20.0 kPa. The objective is to ultimately recover scrap tires-derived pyrolytic carbon blacks with good mechanic al properties of the final vulcanizates. Pyrolytic carbon black physic ochemical properties such as ultimate and proximate analyses and bulk and surface composition, were investigated. The decomposition of rubbe r parts in the tires is almost completed at 420-degrees-C. However to remove all of the hydrocarbons from carbon black pores, a temperature of 500-degrees-C is needed. At higher temperatures, deposition of pyro lytic carbon black on the original carbon black particles takes place. The most significant difference between pyrolytic carbon blacks and c ommercial blacks resides in the former's high inorganic material conte nt. Composition of the inorganics in the pyrolytic carbon black change s with pyrolysis temperatures.