THERMAL-BEHAVIOR OF FULLERENES IN DIFFERENT GAS ATMOSPHERES

The reactivity of a C-60+15% C-70 fullerene mixture in various gases w as studied using thermal analysis (TG/DTA) and infrared spectroscopic techniques. The thermal behavior of fullerenes was found to be complex and strongly dependent on the heating rate, overlapping of different phenomena taking place. Comparison with the behavior of a number of ca rbon materials showed that the reactivity of fullerenes in air is simi lar to that of the least ordered forms of carbon. An interesting featu re is the appearance of various exothermal O-2 gasification peaks as t he heating rate is increased. C-60 undergoes concurrent sublimation an d partial decomposition during heat treatment, leaving carbonaceous re sidues which are partially or totally gasified depending on the reacti vity of the surrounding atmosphere. Condensed solids from the sublimat ion process could be recovered on the cool parts of the thermobalance; mixtures richer in C-60 than the starting one were obtained in Ar whe reas heating in CO2 led to recovery of oxygenated fullerene derivative s. Carbonaceous residues from pyrolysis in Ar and CO2 were strong infr ared absorbers and contained oxygenated (epoxy and carbonyl) functiona l groups. Copyright (C) 1996 Elsevier Science Ltd