THE SURFACE MODIFICATION OF GRAPHITE POWD ER BY DIRECT FLUORINATION .2. THE EFFECT OF FLUORINATION TEMPERATURE

The changes of the surface properties of graphite powder with direct f luorination in the temperature range from room temperature (RT) to 300 -degrees-C were investigated by measuring dispersion stability and wat er adsorption. The state of the fluorine atoms on the graphite surface s was also examined by XPS analysis. The dispersion stability of graph ite powder in water largely increased by surface modification of direc t fluorination at RT, and decreased gradually with increasing fluorina tion reaction temperature. Also, graphite powder with surface fluorina tion at 300-degrees-C did not invade in water, but floated on the surf ace of water. The water adsorption showed that the surface fluorinatio n at RT provided hydrophilic graphite powder, increasing dispersion st ability. While the surface fluorination at higher reaction temperature provided gradually hydrophobic graphite powder, decreasing dispersion stability. The hydrophilic surface comes from introduction of the ion ized fluorine atoms, while the hydrophobic surface comes from formatio n of the C-F covalent bonding, according to the XPS analysis.