Rigid-rod copolymer compositions and the polymeric fibers fabricated from those compositions for enhanced flame resistance

A fiber formed from a polymer of the formula A, B, C or D

• where Z is —O— or —S— in the case of formulas A and B;
• Z is —O—, —S— or —NH— in the case of formulas C and D;
• and in formulas C and D, when Z is —NH—, y can be —C═ or —N═ and when Z is —O— or —S—, y is —C═;
• and when Z is —S—, the bisthiazole rings in the benzobisthiazole moieties may have a cis or a trans orientation;
• m is about 70 to 90 mole % and n is about 10 to 30 mole %.

A flame resistant material formed from a polymer of the formula A, B, C, or D

• where Z is —O— or —S— in the case of formulas A and B;
• and Z is —O—, —S— or —NH— in the case of formulas C and D;
• and in formulas C and D, when Z is —NH—, y can be —C═ or —N═ and when Z is —O— or —S—, y is —C═;
• and when Z is —S—, the bisthiazole rings in the benzobisthiazole moieties may have a cis or a trans orientation;
• m is about 70 to 90 mole % and n is about 10 to 30 mole %.