Measurement of Carbon Black Particles by the Electron Microscope and Low Temperature Nitrogen Adsorption Isotherms

Electron micrographs and nitrogen adsorption isotherms have been compared on six commercial carbon blacks as methods for obtaining particle size and surface area values of finely divided materials. Good agreement between the two procedures was obtained for four of the backs: Grade 6, P 33, acetylene black, and lampblack. For two blacks known to be porous, Mogul and after-treated lampblack, the areas, as measured by the nitrogen isotherms, were 5 to 7 times as large as one would calculate from the electron microscope results.