Effect of stretching on the orientation structure and reaction behavior of PAN fiber during the thermal stabilization

The evolution of structures and properties of Polyacrylonitrile (PAN) precursor fiber during the thermal stabilization was directly related to the mechanical properties of carbon fiber. In the present study, the effects of stretching on the orientation structure and reaction behavior of PAN fibers at different thermal stabilization stages were experimentally investigated. The multi-dimensional structural characterization and mechanical properties tests were used, such as XRD, FT-IR, 13C-NMR, Raman and material testing machine, etc, which would help to reveal the evolution mechanism of the microstructure and reaction behavior of PAN fiber during the thermal stabilization. The results showed that in the process of thermal stabilization, stretching caused the rearrangement of crystalline orientation structure, promoted the cyclization reaction process at higher temperature (>200 C), and furthermore promoted the formation of oriented aromatic like lamellar structure. It can be found that when the drawing ratio of 10% and the exposed temperature at 200 C were applied to the PAN fiber, the increasing of crystalline orientation was obvious and more aromatic lamellar structures generated. Based on the above process technology, the carbon fiber with the higher graphitization degree and better mechanical properties was finally obtained.