The micropores of the rayon based carbon fiber precursors were studied during the pyrolysis process. Results indicated that the longitudinal radius of the micropores increased gradually from 3. 88 nm to 7. 04 nm while the evolution trend of transversal radius was inverse which decreased to 3. 15 nm from 3. 86 nm, thus the shape of the mirocpores became needle. Meanwhile, the fractal dimension of transversal micropores increased from 2. 40 to 2. 61 and the fractal dimension of longitudinal micropores fluctuated in the process from 2. 00 to 2. 23, which indicated the roughness of the micropores increased gradually. The micropore is a major factor in controlling the mechanical property of fibers, therefore it''s important to study the micropores. |