FRACTAL ANALYSIS OF COMMERCIAL AND PYROLYTIC CARBON-BLACKS USING NITROGEN ADSORPTION DATA

The surface fractal dimension of commercial rubber-grade carbon blacks and of pyrolytic carbon blacks (CBP) was determined using nitrogen so rption data. The CBP were produced by vacuum pyrolysis of used tires a t different temperatures and pressures. Commercial carbon blacks and C BP obtained at low pyrolysis pressures have a similar Fractal dimensio n of the surface (D-S) or roughness. CBP produced at higher pyrolysis pressures have a smaller Fractal dimension than commercial grades, sug gesting a smoother surface. Complementary SIMS;ind ESCA investigations showed that the decreasing fractal dimension with increasing pyrolysi s pressure is due to the formation of carbonaceous deposits on the CBP from the pyrolyzed organic material.