Surface and bulk structure of carbon black studied by scanning tunneling microscopy and wide angle scattering
Mechanical properties of rubber are influenced by the type of filler and its structure. One prominent filler is carbon black. It is known that the mechanical properties of the blend depends on a thermal pre-treatment of the carbon black, called graphitizing process. To study the structure of surfaces at a length scale of nanometer scanning tunneling microscopy is well appropriate. However, the information gain is limited to surface structure. Therefore it is useful to perform additional wide-ahgle-X-Ray-scattering experiments to gain insight into the bulk material. We show that the lateral and vertical dimensions of the crystallites of carbon black increase due to the graphitizing process whereas the spacing within the different graphite layers decreases. The analogy to highly oriented pyrolytic graphite is also shown.