Carbon Mesophase-based Composites with Electro / Magnetic Properties

This paper presents the characteristics of composites with mesophase pitch matrix and different types of nanoparticles used as filler. Carbon mesophase generated as carbonaceous particles with diameters of 1 to 100 μm is produced, when a pitch is heated at temperatures between 400 and 460°C. The structure of mesophase spheres is based on aromatic molecules, which are associated and form liquid crystals that are stacked parallel one to each other, the edges of aromatic molecules being exposed to the surface. The surface of mesophase spherules can be modified by various chemical reactions with the hydrogen from the edges. The morphological evolution of mesophase in the presence of filler particles (nanocarbon from different precursors, nanoiron embedded in carbon, carbon nanotubes/nanofibers) was watched in relationship with their electrical/magnetical properties. The morphology was investigated by optical microscopy, atomic force microscopy, scanning electron microscopy, transmission electron microscopy and X ray diffraction analyses. The composites samples were characterized by measuring the electrical resistivity and by studying magnetical behaviour.