DIRECT CARBONIZATION OF PBO FIBER

Poly p-phenylene benzobisoxazole (PBO) fiber appears to display unusua l characteristics during its conversion to carbon fiber. This introduc tory study focused on specific aspects of the carbonization behavior t hat differentiate PBO from other materials. Results showed that oxidat ive stabilization did not affect the tensile properties of carbonized fiber produced from PBO precursor fiber. Unlike other polymeric precur sors, unstabilized PBO fibers could be directly converted to carbon fi bers with promising mechanical and thermal properties. The carbonizati on characteristics of unstabilized PBO were found to be similar to tho se of stabilized PAN-based fibers. However, the PBO-based carbon fiber s exhibited a radial texture similar to pitch-based fibers. Surprising ly, the PBO-based carbon fibers exhibited electrical resistivities in the range of commercial pitch-based fibers, implying that their therma l conductivities also will be similar. Low-temperature carbonization s tudies showed that PBO fiber can be carbonized at rapid rates without adversely affecting the tensile properties of the carbonized material. Its ability to be directly carbonized, combined with the unusual ther mal properties of the final carbon fiber, may make PBO an attractive p recursor for some carbon fiber applications.