Diffusion and flow birefringence of alkylene-aromatic thermotropic polyesters

Hydrodynamic and optical properties of dilute solutions of polydecamethylene-terephthaloyl-di-p-oxybenzoate (P-10-TOB), polypentamethylene-terephthaloyl-di-p-oxybenzoate (P-5-TOB) and polytetramethylene-terephthaloyl-di-p-oxybenzoate (P-4-TOB) in dichloroacetic and trifluoroacetic acids were investigated by translational diffusion, velocity sedimentation, viscometry and flow birefringence. The results of hydrodynamic investigations are interpreted from the standpoint of theories taking account of the draining effect in macromolecules. It is shown, on the basis of hydrodynamic and optical data, that the equilibrium rigidity of molecules (the Kuhn statistical segment) is several times higher for P-10-TOB, P-5-TOB and P-4-TOB than for polyethyleneterephthalate.