The impregnation of a special grade PAN precursor,fibers wus carried out in a 8 wt% KMnO4 aqueous solution to obtain modified PAN precursor fibers. The effects of modification on the chemical stncture and the mechanical properties of precursor fibers thermally stabilized and their resulting carbon fibers u＇ere characterized by the combiination use of densities, wide-angle X-ray diffraction （WAXD）, X-ray photoelectron speetroscopy （XPS）, elemental analysis （ EA ）, Fourier traasform infrared spectroscopy （FT-IR） and scanning electron microscope （SEM）, etc.KMnO4 as a strong oxidizer can swell, oxidize and corrode the skin of a precursor.fiber, and transform C≡N groups to C≡N ones, meamchile , it can decreuse the crystal .size increuse the orientation index and the costallinity index, furthermore it can increuse the densities of modified PAN precursors and resuhing thermally stabilized fibers. As a result, the carbon fibers developed from modified PAN fibers show an improvement in tensile strength of 31.25 % and an improvement in elongation of 77.78 % , but a decrease of 16. 52% in Young＇s modulus.
