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Abstract

The present invention provides processes for producing polybenzazole fibers where a spinning dope containing a polybenzazole polymer in an acid solvent is extruded through a spinning nozzle, followed by coagulation in a coagulating medium and washing with a fluid capable of dissolving the acid solvent; thereafter, in one process, the fiber obtained by the coagulation under specific conditions and the subsequent washing is dried in a heating zone with at least 80% part based on the total length thereof being set at a temperature of 240.degree. C. or higher, and in the other process, the fiber obtained by the coagulation under the conventional conditions and the subsequent washing is neutralized with a basic solution, followed by washing with a fluid capable of dissolving the basic solution, and then dried at a specific temperature set depending upon the residual moisture content in the fiber. The present invention further provides a polybenzazole intermediate predried fiber having a residual moisture content of about 25% and exhibiting a single peak for liquid freezing in the fiber over a temperature range of from 20.degree. to -70.degree. C. when measured by differential scanning calorimetry (DSC).

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First Claim