Abstract
The effect of structural evolution polyacrylonitrile (PAN) on mechanical properties was investigated in stabilization and carbonization. PAN spun fibers were stabilized in a convection oven with a constant tension for various times at 250℃. Fourier Transform Infrared spectroscopy (FTIR) and gel fraction results suggested that intra and intermolecular stabilization reactions occurred simultaneously. X-ray diffractograms revealed a disruption of crystalline structure and an appearance of pre-graphitic structure of PAN fibers due to stabilization. These structural changes by stabilization resulted in the significant decrease of tensile properties of fibers. In Raman spectra with heat treated fibers from 400℃ up to 1200℃, the intensity ratio of the D to G bands (ID/IG) decreased as heat treatment temperature increased, indicating an increase of basal plane of graphitic layer of heat treated fibers. Tensile strength of heat treated fibers at 1200℃ was found to be as high as 2.2 GPa.
Highlights
Carbon fibers are manufactured from three precursor materials such as rayon polyacrylonitrile (PAN), and mesophase pitch
X-ray diffractograms revealed a disruption of crystalline structure and an appearance of pre-graphitic structure of PAN fibers due to stabilization
The longer stabilization time led to the higher extent of reaction (EOR) value: 0 to 0.91 with stabilized fibers for 5 to 180 min
Summary
Carbon fibers are manufactured from three precursor materials such as rayon polyacrylonitrile (PAN), and mesophase pitch. Due to low productivity of rayon-based CF, PAN and mesophase pitch have been more preferred. Mesophase pitch-based CFs are inferior to PAN-based CF in tensile strength [1]. PAN has been most widely used materials for carbon fiber precursors for more than thirty years. To produce PAN-based CFs, three stages are required: wet spinning, stabilization, and carbonization. The nitrile groups in PAN with a large dipole provide high cohesive energy density and chain stiffness, which result in excellent tensile strength [6]. Stabilization is one of the most important factors to determine mechanical strength of PAN based carbon fibers. Fitzer et al reported optimization of stabilization of PAN fibers and effect of carbonization of resulting fibers on tensile strength [4].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
