Continuous heating stabilization of laser-modified PAN fibers

To address the challenges of temperature control and energy waste caused by stepped heating and multiple temperature zones during the pre-oxidation process of polyacrylonitrile-based carbon fibers, this study proposes a continuous heating pre-oxidation method using laser tilted irradiation. Pre-treatment with a 10.6 μm laser and continuous heating pre-oxidation with 976-nm laser tilted irradiation were employed. The pre-oxidation characteristics under different laser irradiation tilt angles were investigated using Raman spectroscopy (RS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and bulk density measurement. The results show that the fiber obtained under irradiation at a 20° laser tilt angle exhibits the smallest core-sheath structure, a Raman R value of 1.82, a pre-oxidation index (SI) of 99.57%, a cyclization rate of 69.67%, and an oxygen content of 9.84%. This indicates that the laser continuous heating pre-oxidation process can effectively suppress the formation of the core-sheath structure, and the prepared samples meet the standards of traditional pre-oxidized fibers (SF).