Thermal analysis of the oxidation of natural graphite - effect of particlesize

The oxidation of natural graphite particles with a prismatic (flake-like) s tructure was investigated by thermal gravimetric analysis (TGA) and differe ntial thermal analysis (DTA). The objective of this study is to examine the relationship between the relative fraction of edge sites and the oxidation behaviour of graphite. The approximate prismatic structure of the natural graphite provided a model geometry from which the relative fraction of edge and basal plane sites was determined. The three thermal parameters, igniti on temperature (T-i), temperature maximum (T-m) in the DTA curves, and the temperature at which 15 % carbon weight loss is attained (T-15), were deter mined for a series of natural graphite samples (average particle size, 2-40 mu m) using simultaneous TGA/DTA. The results reported in this study suppo rt the observation that the fraction of edge sites has a strong influence o n the thermal parameters (T-i, T-m and T-15) for the oxidation of graphite. (C) 2000 Elsevier Science B.V. All rights reserved.