Abstract
AbstractThe surface modification of polyacrylonitrile (PAN) fibers with boric acid was utilized to modulate the homogeneity of the radial structure of the PAN fibers during thermal stabilization. Exothermic peaks of the fibers were put off by boric acid, and unreacted nitrile groups of the oxidized PAN fibers increased with the boron content, indicating that boric acid on the fiber surface had an retardant effect on the thermal stabilization of PAN fibers. The relative skin thicknesses of the oxidized PAN fibers were quantitatively measured by sulfuric acid etching and SEM observation. The value increased obviously with the boron content, which could be further elevated by increasing stabilization time or decreasing stabilization temperature. Oxidized PAN fibers with more homogeneous radial structure can thus be obtained with the modification of boric acid, which might be beneficial for the preparation of high performance carbon fibers.
Highlights
The physical properties of three PAN fibers were followed, PAN fiber, PAN fiber treated with 80°C water, and PAN fiber modified with boric acid
After thermal stabilization at 260°C, the nitrile groups of the original PAN fiber decreased and the value of the fraction of unreacted nitrile groups increased with boron content
The relative skin thickness of the fiber increased with boron content, which can be further elevated with the retention time of the stabilization whatever the boron content was
Summary
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