Fluorination of carbon black

The kinetics of the fluorination of carbon black and the properties of the graphite fluoride prepared are discussed in comparison with those of graphite and petroleum coke. An appreciable weight increase is observed in the fluorination of carbon black even at room temperature because of the large surface area. The increment is approximately proportional to the surface area except for the heat-treated carbon black, and more than twice that of adsorption corresponding to the monolayer of fluorine. An iodide ion is oxidized to iodine by the adsorbed fluorine in the products. The reactivity of carbon black with fluorine decreases with increasing the crystallinity, and the product prepared from the lower crystalline carbon black is less thermostable. The reaction kinetics of carbon black with fluorine is similar to that of graphite, but the diffusion controlled regions are not present in the former. The fluorine content of the graphite fluoride prepared increases with decreasing heat-treatment temperature and with increasing reaction temperature. The crystallinity of the product increases with increasing heat-treatment temperature and with increasing reaction temperature. The heat of immersion of the product inn-butyl alcohol is equal to that of polytetrafluoroethylene.