Dynamic Viscoelastic Behavior of the Liquid Crystalline Side-Chain Polymers

Abstract

Dynamic viscoelastic properties of three liquid crystalline polymers with different spacer length (n) were investigated with parallel-plate simple shear geometry and under uniaxial extension geometry. Temperature dependence curves of G' for the polymers were obtained at various frequencies. It was found that the slope of G' above T _cl was smaller than that below T _cl. In particular, G' of the polymer with the shorter spacer length (n = 5) varied very slowly with the temperature above T _cl. The values (10³-10⁵ dyne/cm² varied with the frequency) of this quasi-plateau modulus indicate that the plateau region is not due to the entanglements between the main-chain. The existence of loose entanglements between the large, rigid side chains is suggested.