Characterization of modified and original carbon blacks from pyrolysis of scrap tires

Key words: 
• pyrolytic carbon black /
• modification /
• SEM /
• XPS

Abstract: Nitric acid washing and stearic acid modification were used to modify the carbon black from atmospheric pyrolysis of scrap tires. Pyrolytic carbon black, acid washed carbon black and acid washed carbon black modified with stearic acid were prepared. In order to study the properties of the modified samples, the carbon blacks were characterized by SEM and XPS. The results showed that high ash concentration in pyrolytic carbon black decreased from 20.5% to 4.0% after acid washing. Meanwhile, the BET surface area increased from 54.92 m2/g to 69.62 m2/g with the particle size decrease and the DBP absorption number was improved to 170 mL/100 g.Acid washed carbon black modified with stearic acid had lower BET surface area and DBP absorption number than acid washed carbon black. According to XPS analysis, the carbonaceous deposits on the surface of pyrolytic carbon black made its surface polarity decrease. Acid washed carbon black had lower C—C/C—H groups, higher C—OR, C—OEt and COOR or COOH groups on its surface. There was no much change in surface carbon groups between acid washed carbon black and acid washed carbon black modified with stearic acid. The content of surface doublebonded oxygen in acid washed carbon black modified with stearic acid was higher than pyrolytic carbon black and acid washed carbon black.