" Mesophase " - Pitch - Based Carbon Fibers : Part ‡ U Mechanical Properties and Thermal Expansion

Mechanical properties such as strength, modulus and strain to break, and coefficients of thermal expansion of mesophase-pitch-based carbon fibers were measured using the fibers with four different microtextures heat-treated at two different temperatures. The textures were radial with wedge, radial, random and onion. In strain to break of the fibers, there were not so much difference with different microtextures. Young's moduli, however, were different with microtextures, especially in graphitized fibers. The modulus correspond to the orientation function, and to crystallographical parameters. The fiber with higher modulus seemed to be stronger. Coefficients of thermal expansion of the carbonized fibers were able to be classified into two groups; those of the fibers with radial with wedge/random and with radial/onion, but those of graphitized ones were in the same level. The coefficients were smaller than those of PAN-based fibers with the same Young's moduli.