PREPARATION AND CHARACTERIZATION OF CARBON AEROGELS

Carbon aerogels can be used in various different study areas thanks to their attractive features such as high porosity, its easily controlled pore structure, low electric resistance, high electrical conductivity, and its thermal and mechanic aspects. In this study, Resorcinol-Formaldehyde (RF) gels were synthesized by using the sol-gel technique. Then, the drying process was carried out with carbon dioxide gas under the supercritical conditions. A carbon aerogel was produced by pyrolysis of RF gel obtained in previous step by using nitrogen gas. Activation process was carried out with carbon dioxide gas at pyrolysis stage at different times in order to increase surface area. It is found that the best activation is activation with carbon dioxide gas for 40 minutes after the pyrolysis process with nitrogen gas for 7 hours and 20 minutes. The surface area of carbon aerogel obtained from experiments under the best activation conditions at a fixed resorcinol/formaldehyde (R/F) ratio and by changing resorcinol/catalyst (R/C) and resorcinol/water (R/W) was found 1112 m(2)/g. Drying period of RF aerogels under the super critical conditions is quite long. In order to reduce this period, the drying process was conducted by using carbon dioxide and ethanol mixture. Therefore the drying period was reduced by nearly half.