Macromolecular Division Commission on Polymer Characterization and Properties Working Party on Structure and Properties of Commercial Polymers* Characterization of Commercially Available Pan (polyacrylonitrile)-based Carbon Fibers

The characterization of high performance PAN—based carbon fibers is described. The process of conversion of polyacrylonitrile fibers into carbon fibers consists mainly of two sequent steps, namely stabilization and carbonization. The ladder structure consisting of acridone ring (40%), naphthyridine ring (30%) and hydronaphthyridine ring (20%) as shown in Fig.5 was assigned for the chemical structure of fully stabilized fibers. Structure characterization of carbon fibers was carried out by the use of the techniques such as scanning electron microscopy, transmission electron microscopy, electron diffraction and electron energy loss spectroscopy. Surface of carbon fibers and also the interface between the surface and the matrix plastics were studied utilizing various kinds of surface and microanalytical techniques. XPS has proven to be effective in obtaining useful informations. The use of additional techniques such as Raman microprobe, FT—IR, solid state high—resolution NNR and secondary ion mass spectrometry are described. The characteristic features of carbon fibers are high tensile modulus and high tensile strength combined with low specific gravity. Following items about mechanical properties of carbon fibers are discussed: multifilament tensile test which is useful for measuring tensile strength distribution of single filaments, relation between tensile strength of filaments and structural parameters, and relation between tensile strength of filaments in air and those within composites.