In-Situ Synchrotron WAXD/SAXS Studies of Structural Development during PBO/PPA Solution Spinning
Combined wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) studies using synchrotron radiation were carried out to investigate the structural development during in-situ solution spinning of poly(p-phenylenebenzobisoxazole) (PBO) in poly(phosphoric acid) (PPA). WAXD patterns...
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Veröffentlicht in: | Macromolecules 2002-01, Vol.35 (2), p.433-439 |
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Hauptverfasser: | , , , , , , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Combined wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) studies using synchrotron radiation were carried out to investigate the structural development during in-situ solution spinning of poly(p-phenylenebenzobisoxazole) (PBO) in poly(phosphoric acid) (PPA). WAXD patterns indicated that the structure in the extruded PBO/PPA dope before coagulation (in water) possessed lyotropic “biaxial nematic” nematic order involving PBO−PPA complex as the mesogenic unit. A different biaxial nematic order in pure PBO was found to develop immediately upon coagulation in water. When the coagulation time exceeded 30 min, the complex PBO/PPA structure completely disappeared, and well-oriented PBO crystals were formed. The meridian peaks exhibited long streaks, indicating a translational disorder of PBO molecules in the fiber direction. SAXS patterns of the PBO fiber after coagulation showed equatorial streaks with no further maxima observed, which is attributed to a microvoid structure. |
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ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/ma010249g |