| 摘要 |
High oriented poly(p-phenylenetetraphthalamide) short fibers having an inherent viscosity of at least 5.0 and a dimension of 2-12 mu m in diameter and 1000-5000 mu m in length are provided. These fibers have a physical form of irregular cross-sections and needle point-like ends similar to those of natural wood pulp fibers, and crystalline properties such as a crystallinity of more then 50%, an orientation angle of less than 25 DEG and an apparent crystallite size of more that 50 ANGSTROM as determined from an X-ray diffractogram scan, and a cross-section with four extinction positions through 360 DEG rotation when observed under a polarizing microscope. These fibers are prepared, without spinning steps, by subjecting the molecular chains of poly(p-phenyleneterephthalamide) to mechanical parallelization during the growth of the chains in a polymerization system therefor containing a pyridine/amide-based solvent.
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