A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

Abstract

ABSTRACT The thermal behavior of graphite, C60 fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA–DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C60 and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed. The combustion reaction in air flow of graphite, C60 and C70 fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA–DTA at a heating rate of 20°C/min. C70 fullerene and fullerene black have been found to be the most reactive carbon materials with O2. The role played by C70 in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O2 attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C60 fullerene appears closer to that of graphite although it appears to be more reactive with O2. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA–DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.