Étude de la phase nématique d'un poly (téréphtalamide de paraphénylène)

Abstract

2014 On a étudié au moyen de la microscopie optique et de la diffraction des rayons X les solutions concentrées anisotropes d'un poly(téréphtalamide de paraphénylène) dans l'acide sulfurique pur. On a mis en évidence la texture à fils caractéristiques des cristaux liquides nématiques et on a discuté ses traits principaux. On a ensuite déterminé l'évolution de la distance d'approche des macromolécules en fonction de la dilution ; on peut en conclure que celles-ci ont une conformation très étirée, proche de la conformation à l'état cristallin.

Structural investigations of polymer liquid‐crystalline solutions: Aromatic polyamides, hydroxy propyl cellulose, and poly(γ‐benzyl‐L‐glutamate)

“…If we presume such an array to exist in the planes perpendicular to the pitch and take d l and d2 as characteristic distances in the plane parallel and perpendicular to macromolecules and ds the perpendicular distance between layers, we can write gdld2d3 = const The variation of pitch with concentration is shown in Figure 9 for the PyBLG and HPC solutions. It varies approximately as p = K+-" (6) where a is 2 for PyBLG and 8 for the HPC solutions.…”

High-Performance Fibers

“…This is due to the chain rigidity leading to highly extended chain configuration. The conformation of PPTA and poly(1,4-benzamide) chains is nearly as extended as in a crystal with persistence length of 175 and 500 Å, respectively [60][61][62]. These values are about 25-50% of the chain length of molecular mass of 20 000.…”

Band texture formation of sheared polymeric liquid crystalline state

“…The growth of nematic domains of this and other systems on standing was also observed by Skoulios et a1. [29,30] without mentioning of band appearance. In fact, Elliott et al [l] long ago also noticed the band formation in the process of film formation from a solution of PBLG/CHCl, and attributed it to the effect of local orientation caused by evaporation of the solvent.…”