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
Hauptverfasser: Ran, Shaofeng, Burger, Christian, Fang, Dufei, Zong, Xinhua, Cruz, Sharon, Chu, Benjamin, Hsiao, Benjamin S, Bubeck, Robert A, Yabuki, Kazuyuki, Teramoto, Yoshihiko, Martin, David C, Johnson, Michael A, Cunniff, Philip M
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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.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma010249g