POLYBENZAZOLES AND POLYBENZAZOLE PRECURSORS

1 . A fiber, pulp, fibril, or fibrid comprising polybenzazole having a repeating unit of formula (I) and/or (II)

wherein Ar 1 and Ar 2 are independently an aromatic group having 4 to 12 carbon atoms, Ar 1 has the para configuration, and

X and Y are the same or different and selected from O, S, and NH; and

wherein fiber contains between 30.1 ppm and 1500 ppm of non-extractable phosphorus compound, and pulp, fibril, or fibrid contains less than 1500 ppm of non-extractable phosphorus compound if X and Y are the same.

2 . The fiber, pulp, fibril, or fibrid of claim 1 comprising 40-100 mole % of the repeating unit (I) and/or (II) and to a total of 100 mole % of a repeating unit of the formula (III)

3 . The fiber, pulp, fibril, or fibrid of claim 2 comprising 60-100 mole % of the repeating unit (I) and/or (II) and to a total of 100 mole % of the repeating unit of the formula (III).

4 . A fiber, pulp, fibril, or fibrid comprising a polybenzazole precursor comprising a repeating unit, wherein an aromatic group is substituted with group XH and optionally with group YH, having formula (IV):

wherein Ar 1 and Ar 2 are independently an aromatic group having 4 to 12 carbon atoms, Ar 1 and Ar 2 have the para configuration, X and Y are the same or different and selected from O, S, and NH, and n is 0 or 1.

5 . The fiber, pulp, fibril, or fibrid of claim 4 comprising 40-100 mole % of the repeating unit (IV) and to a total of 100 mole % of a repeating unit of the formula (III)

6 . The fiber, pulp, fibril, or fibrid of claim 5 comprising 60-100 mole % of the repeating unit (IV) and to a total of 100 mole % of the repeating unit of the formula (III).

7 . The fiber, pulp, fibril, or fibrid of claim 1 wherein Ar 1 and Ar 2 are independently selected from:

8 . The fiber, pulp, fibril, or fibrid of claim 7 wherein Ar 1 and Ar 2 are a benzene moiety, or Ar 1 is a phenylbenzene moiety and Ar 2 is a benzene moiety, and X is O.

9 . The fiber, pulp, fibril, or fibrid of claim 4 wherein the polybenzazole comprises at least the aromatic groups with the formulae:

10 . A method of obtaining the fiber, pulp, fibril, or fibrid of claim 1 comprising the steps of:

extruding a solution comprising 25 to 100 mole % of a polybenzazole precursor and to a total of 100 mole % of polybenzazole polymer in a phosphoric acid-free dope through a die or spinneret to obtain a fiber, pulp, fibril, or fibrid;

drawing the fiber across an air gap;

coagulating the fiber, fibril, pulp, fibrid or film in a coagulation bath;

optionally washing the fiber, fibril, pulp, fibrid or film; and

optionally drying the fiber, fibril, pulp, fibrid or film;

heat treating the fiber, fibril, pulp, fibrid or film to convert the polybenzazole precursor consisting of repeating units selected from

to the polybenzazole polymer consisting of repeating units selected from

wherein Ar 1 and Ar 2 are independently an aromatic group having 4 to 12 carbon atoms, Ar 1 has the para configuration and 40 -100% of the repeating units are repeating unit I and/or repeating unit II and wherein the polybenzazole contains less than 1500 ppm of non-extractable phosphorus compound if 100% of the repeating units are repeating unit I and/or repeating unit II and X and Y are the same;

optionally followed by washing and drying steps.

11 . The method according to claim 10 wherein heat treating the fiber or pulp is performed under an inert atmosphere at 250 to 600° C. for 0.5 sec to 24 h.

12 . The method according to claim 10 wherein the dope is water, sulfuric acid, or NMP/CaCl 2 .

13 . The method according to claim 12 wherein the dope is water having pH>8.

14 . The method according to claim 13 wherein the dope is water containing sodium hydroxide and/or tetramethylammonium hydroxide.