Mechanical Dynamic Properties of a Main Chain Liquid-Crystalline Copolyether

Abstract

The study of the mechanical dynamic properties of the LC copolycther-poly(4,4′-dihydroxy-α-methylstilhene-hexyl(nonyl)methylene)—has yielded evidence for the possibility of obtaining stationary states in the nematic phase. These stationary states can be achieved either by annealing at least for four days or by prolonged shear (at least for two days) of the annealed samples by using a given strain amplitude and frequency. The stationary states are characterized by constant and reproducible moduli. The moduli determined after shear obey the time-temperature superposition, but the shift factors are unusually small. The transition from the nematic into the isotropic phase is charactcrized by an important jump in both the respective moduli and the dynamic viscosity.