Radiation oxidation and subsequent thermal curing of polyacrylonitrile fiber

Polyacrylonitrile (PAN) fibers were exposed to gamma-ray irradiation at room temperature under vacuum, air and oxygen to investigate the radiation oxidation effects on PAN fibers. Radiation-induced oxidation degradation and crosslinking was evaluated by measuring the gel fraction. It was found that radiation oxidation took place mainly on the fiber surface due to the limited penetration of oxygen into PAN fibers from the surface, and the oxidation thickness increased with the oxygen pressure. Chain scission was dominant in the oxidized area, and crosslinking occurred in the inner part of the fibers. However, the oxidized regions of the fibers can be converted to gel via crosslinking by thermal curing at 160 degrees C in a N-2 atmosphere. Higher extents of radiation oxidation degradation led to a greater increase in the gel fraction. These results suggest that the radiation treatment of PAN fibers prior to thermal oxidation may be useful for manufacturing carbon fibers. (C) 2013 Elsevier Ltd. All rights reserved.