| Popis: |
Eleven commercial carbon blacks, one anthracite, and three graphites were studied. Changes in the crystallographic and physical properties upon oxidation and heat treatment were followed by measurements of helium densities, nitrogen low temperature adsorption surface areas (BET), crystallite sizes, and average range of inhomogeneities and surface areas calculated from small-angle X-ray scattering data. On the basis of their change in properties, the carbons can be classified into two main groups. Group one: These carbons show a large decrease in helium density and BET surface area and an increase in particle density upon heat treatment, indicating the production of an extensive closed pore system. Group two: The carbons show an increase in helium and particle densities and a very slight decrease in BET surface area upon heat treatment, indicating the development of a dense, compacted particle structure. The X-ray surface areas and average range of inhomogeneities for the carbons are compared with the BET surface areas and crystallite dimensions, respectively. |
