Formation and Properties of Hard Carbon I. Carbonization of Xylene-Formaldehyde Resin

The purpose of this study is to elucidate the effect of crosslinking on the properties of carbonization products, that is glassy carbons, from thermosetting resins. In this paper the thermosetting xyleneformaldehyde resin was carbonized at 300-1400℃, and the micro-Vickers hardness of carbonization products and their thermal behavior under air oxidation were studied. Hardness increased abruptly at the carbonization above 700℃ and attained the maximum value 290-300 kg/mm2 at 1000-1100℃. This value is the same level as or superior to the industrial glassy carbon materials from Tokai Carbon Co., LTD. Differential thermal analysis curve of the sample carbonized at 1000℃ under air oxidation showed only one exothermic peak above 500℃ with the maximum at 620-650℃. The thermal behavior is similar as that of active charcoal, but clearly different from that of the industrial glassy carbon which showed two exothermic peaks. The higher the carbonization temperature of precursor resin was, the higher the temperature at peak maximum was. These results were discussed based on the ribbon structure model of glassy carbon. The relation between the heat of oxidation calculated from peak area of DTA curve and the carbonization temperature was also discussed