Process for the preparation of polybenzazole filaments and fiber

Details Process for the preparation of polybenzazole filaments and fiber Process for the preparation of polybenzazole filaments and fiber

1995-07-12

1996-06-11

Foelak, Morton

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

521 64, 528487, 528499, C08F 600, C08J 926, C08J 928

Patent

active

055256384

ABSTRACT:
Described is a continuous process for removing polyphosphoric acid from a polybenzazole dope filament, which comprises: (a) contacting the dope filament with water or a mixture of water and polyphosphoric acid under conditions sufficient to reduce the phosphorous content of the filament to less than about 10,000 ppm by weight; and then (b) contacting the dope filament with an aqueous solution of an inorganic base under conditions sufficient to convert at least about 50 percent of the polyphosphoric acid groups present in the filament to a salt of the base and the acid. It has been discovered that contacting the dope filament with a solution of a base after washing the filament to remove most of the residual phosphorous advantageously leads to an improvement in the initial tensile strength of the filament, as well as improved retention of tensile strength and/or molecular weight (of the polybenzazole polymer) following exposure to light and/or high temperatures.

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