Research on Improving the Pre‐Oxidation Process of the Excellent Mechanical Strength Carbon Fiber

Abstract

This study used Synchrotron Wide‐Angle X‐ray Diffraction (WAXD) and Synchrotron Small Angle X‐ray Scattering (SAXS) to carry out in‐situ study of the pre‐oxidation process of Polyacrylonitrile (PAN) fibers with two different preparation processes. Through analysis of 2D WAXD/SAXS data, This study divides the evolution of PAN fiber's crystal and microporous structures during pre‐oxidation into three and two stages, respectively. The evolution of PAN fiber's crystal structure during pre‐oxidation can be divided into three stages: 1) Initial stage: small‐sized crystals melt, crystal orientation decreases, and no cyclization reactions occur. 2) Intermediate stage: cyclization reactions happen in the amorphous region, leading to increased crystal size, crystal orientation, and crystallinity. 3) Final stage: cyclization reactions occur in the crystal region, resulting in reduced crystal size and orientation. The evolution of microporous structure can be divided into two stages: microporous shrinkage stage and microporous expansion stage. These features were analyzed using 2D WAXD/SAXS techniques. This study provides valuable references and guidance for the industrial production of PAN fibers by exploring the mechanism of the pre‐oxidation process in‐depth.This article is protected by copyright. All rights reserved

In Situ Study and Improvement of the Temperature Increase and Isothermal Retention Stages in the Polyacrylonitrile (PAN) Fiber Pre-Oxidation Process

“…According to the DSC data, no cyclization reaction occurred at this temperature. Hence, the decreased crystallinity was attributed to melting of the crystals [ 41 ]. Subsequently, after an isothermal retention temperature of 180 °C for 15 min, the diffraction peak intensity of the 100 crystal plane slightly decreased, suggesting a minor reduction in crystallinity and indicating that there was no significant melt of the crystals.…”

Facile Preparation of Polyacrylonitrile-Based Activated Carbon Fiber Felts for Effective Adsorption of Dipropyl Sulfide

“…In contrast, the liquid-phase pre-oxidation reaction is milder, requiring a shorter treatment time and lower temperature. The pre-oxidized fibers prepared in this manner could exhibit a uniform structure and do not develop a skin-core structure [ 20 ]. Therefore, the liquid-phase pre-oxidation method is promising for the fabrication of PAN-ACF felt, although seldom similar works have been reported before.…”