An investigation of the dilute solution properties and liquid crystal behavior of poly(chloro-p-phenylene terephthalamide)

Intrinsic viscosities for these polymer-solvent systems were unusually large, with the values being greater in DMAC/LiCl than in H₂SO₄. As the LiCl concentration was decreased below 2%, both the intrinsic viscosity, and the molecular weight dependency of intrinsic viscosity increased rapidly. At higher temperatures, intrinsic viscosity was shown to decrease.

The polymer concentration required to form a liquid crystalline phase, ø_c, increased with increasing LiCl concentration, and in DMAc containing 4% LiCl, c did not vary significantly with molecular weight. In DMAc containing 3% or more LiCl, ø_c decreased rapidly with increasing temperature, and the values obtained in solvents containing different amounts of LiCl appeared to be converging above 95°.

The dramatic effects of solvent composition and temperature were seen to be a result of increased polymer flexibility in H₂SO₄, and the formation of associated species in DMAC containing LiCl. The degree of association decreased with increasing LiCl concentration, and increased with increasing temperature. In solvents containing 3% or more LiCl, the association phenomenon dominated the phase behavior.