Dynamic birefringence and conformation of molecules of aromatic polyamide-hydrazide in solutions

Abstract

Flow birefringence (FB) in solutions has been investigated for a number of samples of polyamide-hydrazide (PPAH) in dimethylsulphoxide; intrinsic viscosities [η] of the same solutions have been measured. Characteristic values of FB, [η], and orientation angles [χ/g] of the solutions were determined. Molecular weights of the PPAH samples were calculated from values of [χ/ g] and [η]. The use of characteristic values of [ n] and [η] and the theory of optical anisotropy of persistent chains gives quantitative data on the equilibrium rigidity of PPAH molecules. It was shown that the length of the statistical segment of the PPAH chain is 800 Å. The possible reasons for the fact that the equilibrium flexibility of PPAH molecules is greater than that of poly- p-phenylene terephthalamide molecules have been discussed.