Microstructure and nematic transition in thermotropic liquid crystalline fibers and their single polymer composites

Estelle Kalfon-Cohen, Gad Marom, Amotz Weinberg, Ellen Wachtel, Claudio Migliaresi, Alessandro Pegoretti

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12 Scopus citations

Abstract

We describe a new single polymer composite (SPC) prepared from two liquid crystalline vectran fibers. Vectran M is the as-spun fiber while vectran HS is the high-strength version. A study of the morphology of the pristine materials shows that the two fibers have different crystal structures. The wide-angle X-ray diffraction (WAXD) data confirm the presence of the so-called pseudo-hexagonal (PH) unit cell in vectran M, while an orthorhombic structure is revealed in the vectran HS fibers. A transition to the nematic phase is observed by in situ X-ray diffraction at ∼277°C for the M fibers and at ∼315°C for the HS fibers. During the compaction process, the orientation of the reinforcing fibers is well maintained and the transition to a nematic phase seems to be delayed by processing at high applied pressure. Concomitantly, vectran M loses its orientation and the transition to the nematic phase disappears.

Original languageEnglish
Pages (from-to)771-779
Number of pages9
JournalPolymers for Advanced Technologies
Volume18
Issue number9
DOIs
StatePublished - Sep 2007

Keywords

  • Liquid crystalline polymer
  • Nematic transition
  • Single polymer composite
  • WAXD

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