Investigation on promotion effect of oxidative stabilization for pitch‐based fiber by co‐carbonization of coal tar pitch and atmospheric residual

As a pivotal step in the preparation of carbon fiber, oxidative stabilization not only plays a crucial role in maintaining fibrous morphology but also contributes significantly to enhance mechanical properties of resultant carbon fiber. Due to high activation energy of pitch molecules reaction with oxygen and the sluggish diffusion of oxygen within the fiber, the improvement of oxidative stabilization efficiency faces significant challenges. Atmospheric residual (AR) has a high and easily oxidized aliphatic structure. Spinnable pitch is synthesized by co‐carbonization of coal tar pitch (CTP) and AR at a ratio of 3:1 in this work. Its methylene bridge bond ratio is 4.45% and have an appropriate amount aliphatic structure, which makes pitch molecular more linear and naphthenic. Excessive addition of AR is detrimental to spinning performance. The most optimal oxidative stabilization temperature of as‐spun fiber was 280°C, which is lower than that of fiber produced by CTP alone (300°C), displaying a higher oxidative stabilization efficiency. The obtained pitch‐based carbon fiber shows excellent mechanical properties with tensile strength of 999.0 ± 80.1 MPa and Young's modulus of 57.7 ± 3.5 GPa. The co‐carbonization by two different substances has been applied in manufacturing carbon fiber, providing a facile approach to accelerate the oxidative stabilization of pitch fiber. The introduction of aliphatic structure by co‐carbonization of coal tar pitch and atmospheric residual provides more methylene bridge bonds and more α‐hydrogens for spinnable pitch, which makes pitch molecular more linear and naphthenic. The α‐hydrogens of aliphatic structure of the CCA‐3 are easily attacked by oxygen, showing a higher oxidative stabilization efficiency. The obtained pitch‐based carbon fiber shows excellent mechanical properties.