Processes for hydrolysis of polyphoshoric acid in polyareneazole filaments

1. A process for hydrolyzing polyphosphoric acid in a never-dried filament comprising polyareneazole and polyphosphoric acid, the process comprising:

a) passing an extruded dope through a coagulation bath to form a substantially solid polymer filament,

b) removing surface liquid from the substantially solid polymer filament of step (a),

c) contacting the substantially solid polymer filament of step (b) with a hot surface having a temperature of at least about 150° C. to hydrolyze polyphosphoric acid; and

d) removing hydrolyzed polyphosphoric acid from the substantially solid polymer filament of step (c).

2. The process of claim 1 , wherein the hot surface comprises heated rolls.

3. The process of claim 1 , wherein the polyareneazole polymer is a polypyridazole.

4. The process of claim 3 , wherein the polypyridazole is a polypyridobisimidazole.

5. The process of claim 4 , wherein the polypyridobisimidazole is poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole.

6. The process of claim 1 , wherein the polyareneazole polymer is a polybenzazole.

7. The process of claim 6 , wherein the polybenzazole is a polybenzobisoxazole.

8. The process of claim 1 , wherein substantially all of the polyphosphoric acid is hydrolyzed during the contacting of the filament with a hot surface.

9. The process of claim 1 , wherein the filament comprises less than 2 percent phosphorus based on filament weight after removing hydrolyzed polyphosphoric acid from the filament.

10. The process of claim 1 , wherein the surface liquid is removed by evaporation, drying, blowing, absorption, scraping, wicking, stripping, dripping, or any combination thereof.