Structural Evolution of Polyacrylonitrile Fibers in Stabilization and Carbonization

Sungho Lee, Jihoon Kim, Bon-Cheol Ku, Junkyung Kim, Han-Ik Joh

Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeollabuk-do, Korea (South).
Korea Institute of Science and Technology, Seoul, Korea (South).

DOI: 10.4236/aces.2012.22032                

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 (I_D/I_G) 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.

Keywords

Polyacrylonitrile; Stabilization; Carbonization; XRD; Tensile Properties; Carbon Fibers

Conflicts of Interest

The authors declare no conflicts of interest.

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