Analysis of surface groups on carbon blacks

✍ Scribed by P.H. Given; L.W. Hill

• Publisher: Elsevier Science
• Year: 1969
• Tongue: English
• Weight: 895 KB
• Volume: 7
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(69)90519-3

✦ Synopsis

Surface oxygen groups on carbon blacks were analyzed by several new techniques and some methods used previously were re-examined. Phenolic hydroxyl groups were converted to their acetate ester derivatives using radioactively labeled acetic anhydride in pyridine at 90°C. The drop in count rate on hydrolysis indicated a phenolic hydroxyl content ranging from 0.31 to 1.25 m-equiv./g for a series of blacks with a volatile content ranging from 5 to 13 per cent. Only about half of the activity could be removed by hydrolysis. Phenolic hydroxyl groups were also converted to their silyl ether derivatives by treatment with hexamethyldisilazane in pyridine. For all blacks, the extent of silicon incorporation indicated a lower phenolic hydroxyl content than that obtained by acetylation. The total acid content, as determined by direct nonaqueous thermometric titration, ranged from 0.30 to 1.44 m-equiw./g. The thermometric method provided several experimental advantages over methods used previously for determining total acid content. In contrast to previous reports, attempts to study neutral groups by nonaqueous polarography were essentially unsuccessful.