Polyimide Fibers Obtained by Spinning Lyotropic Solutions of Rigid-Rod Aromatic Poly(amic ethyl ester)s

Title data

Neuber, Christian ; Schmidt, Hans-Werner ; Giesa, Reiner:
Polyimide Fibers Obtained by Spinning Lyotropic Solutions of Rigid-Rod Aromatic Poly(amic ethyl ester)s.
In: Macromolecular Materials and Engineering. Vol. 291 (2006) Issue 11 . - pp. 1315-1326.
ISSN 1439-2054
DOI: https://doi.org/10.1002/mame.200600256

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Abstract in another language

Summary: Fibers were spun from a lyotropic solution of a high-molecular-weight ( = 5.89 g · dL-1), rigid-rod, fully aromatic polyimide precursor polymer in a dry-jet, wet-spinning process in NMP. Acetone was identified as the coagulant of choice since fibers could be drawn extensively in this solvent, resulting in improved mechanical properties (tensile modulus: E = 17 GPa, strength at break: break = 400 MPa, elongation at break: break = 5.3%) and orientation, which was shown by WAXS patterns. SEM images showed a layered, skin-core morphology without any visible fibrillation. Additional processing of these fibers by step-wise hot-drawing up to 400 °C under tension rendered oriented polyimide fibers with excellent mechanical properties. (E = 68 GPa, break = 700 MPa, break = 1%). An analysis of the WAXS diffraction patterns showed an improved orientation of the fibers in the axial and lateral directions; however, probably due to the CF3 side groups, the lateral distance was still too large for crystallization. SEM images of these imidized fibers showed, for the first time, a fibrillar morphology in addition to the typical, skin-core, sheet-like morphology.