Abstract: To provide fibers which retain the excellent heat resistance and flame retardancy inherent in polybenzazole fibers and pyridobisimidazole fibers, have improved post-processability and neither necessitate considerable change in production process conditions nor require a high-temperature and long-time heating treatment. With respect to the polybenzazole fiber and pyridobisimidazole fiber, in an electron diffraction diagram of a surface layer part (from the surface to 1 ?m) of the fibers, the fibers containing a crystal present in a state satisfying that S2/S1 is in a prescribed range, wherein S1 is a diffraction peak area derived from a crystal (200) plane and S2 is a diffraction peak area derived from a plurality of other crystal planes along an equatorial direction profile.

Abstract: To provide fibers which retain the excellent heat resistance and flame retardancy inherent in polybenzazole fibers and pyridobisimidazole fibers, have improved post-processability and neither necessitate considerable change in production process conditions nor require a high-temperature and long-time heating treatment. With respect to the polybenzazole fiber and pyridobisimidazole fiber, in an electron diffraction diagram of a surface layer part (from the surface to 1 ?m) of the fibers, the fibers containing a crystal present in a state satisfying that S2/S1 is in a prescribed range, wherein S1 is a diffraction peak area derived from a crystal (200) plane and S2 is a diffraction peak area derived from a plurality of other crystal planes along an equatorial direction profile.

Abstract: The present invention relates to polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics containing in themselves an organic pigment having heat resistance as high as a thermal decomposition temperature of 200° C. or higher, and soluble in a mineral acid and having group(s) of —N? and/or NH— in the molecule, such as any of perinones and/or perylenes, any of phthalocyanines, any of quinacridones, and any of dioxazines, wherein they have a strength retention of 50% or higher when exposed to light from a xenon lamp for 100 hours and having a tensile strength retention of 85% or higher after exposed to an atmosphere of a temperature of 80° C. and a relative humidity of 80% for 700 hours. The polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics can be used for cords for reinforcing rubber, sheets and rods for reinforcing cement/concrete, composite materials, sail clothes, ropes, knife proof vests and bullet proof vests.

Abstract: The present invention relates to polybenzazole fibers which can still have high durability against atmospheres of high temperatures and high humidity even after yarns made thereof have had kink bands therein due to the damages in the course of post-processing for making woven fabrics, knitted fabrics, braids, ropes and cords. The invention also relates to articles comprising the polybenzazole fibers, particularly spun yarns, rubber-reinforcing materials, fiber-reinforced composite materials, woven or knitted fabrics, knife-proof materials or bullet-proof vests, ropes and sail cloths.

Abstract: The present invention relates to polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics containing in themselves an organic pigment having heat resistance as high as a thermal decomposition temperature of 200° C. or higher, and soluble in a mineral acid and having group(s) of —N=and/or NH— in the molecule, such as any of perinones and/or perylenes, any of phthalocyanines, any of quinacridones, and any of dioxazines, wherein they have a strength retention of 50% or higher when exposed to light from a xenon lamp for 100 hours and having a tensile strength retention of 85% or higher after exposed to an atmosphere of a temperature of 80° C. and a relative humidity of 80% for 700 hours. The polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics can be used for cords for reinforcing rubber, sheets and rods for reinforcing cement/concrete, composite materials, sail clothes, ropes, knife proof vests and bullet proof vests.

Abstract: There is provided a polybenzazole fiber or film containing a basic organic compound in the form of a monomer or a condensate, selected from the group consisting of guanidines, triazoles, quinazolines, piperidines, anilines, pyridines, cyanuric acids, and p-phenylenediamine, m-phenylenediamine and a mixture thereof. This fiber has characteristics in that the X-ray meridian diffraction half-width factor is 0.3°/GPa or less, that the elasticity decrement (Er) attributed to change of molecular orientation is 30 GPa or less, and that the breaking strength is 1 GPa or more. This fiber can be used in staple fiber, a spun yarn, a woven or knit fabric, a felt material, a composite material, a cord, a rod, a fibrous sheet, a knife proof vest or a bullet proof vest.