Journal of thermal analysis

, Volume 46, Issue 3–4, pp 719–731 | Cite as

The crystal structures and thermal shrinkage properties of aromatic polyimide fibers

  • Z. Wu
  • A. Zhang
  • D. Shen
  • M. Leland
  • F. W. Harris
  • S. Z. D. Cheng
Article

Abstract

Three aromatic polyimides based on 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA) and three different diamines 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (PFMB), 2,2′-dimethyl-4, 4′-diaminophenyl (DMB) or 3,3′-dimethylbenzidine (OTOL) have been synthesized. These polyimides are soluble in hotp-chlorophenol,m-cresol or other phenolic solvents. Fibers have been spun from isotropic solutions using a dry-jet wet spinning method. The as-spun fibers generally exhibit low tensile properties, and can be drawn at elevated temperatures (>380° C) up to a draw ratio of 10 times. Remarkable increases in tensile strength and modulus are achieved after drawing and annealing. The crystal structures of highly drawn fibers were determinedvia wide angle X-ray diffraction (WAXD). The crystal unit cell lattices have been determined to be monoclinic for BPDA-PFMB and triclinic for both BPDA-DMB and BPDA-OTOL. Thermomechanical analysis (TMA) was used to measure thermal shrinkage stress and strain. A selfelongation has been found in the temperature region around 450°C. This phenomenon can be explained as resulting from the structural development in the fibers as evidencedvia WAXD observations.

Keywords

aromatic polyimide fiber as-spun fiber crystallization crystal structure crystal unit cell draw ratio dry-jet wet spinning isotropic solution modulus self-elongation tensile strength thermal shrinkage stress thermal shrinkage strain thermomechnical analysis triclinic wide angle X-ray diffraction zone drawing 

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Copyright information

© Akadémiai Kiadó 1996

Authors and Affiliations

  • Z. Wu
    • 1
  • A. Zhang
    • 1
  • D. Shen
    • 1
  • M. Leland
    • 1
  • F. W. Harris
    • 1
  • S. Z. D. Cheng
    • 1
  1. 1.Maurice Morton Institute and Department of Polymer ScienceThe University of AkronAkronUSA

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