Rheological and rheo-optical studies of a constitutive equation for nematogenic solutions of rod-like polymers

Abstract

Rheological and rheo-optical studies on solutions of the rod-like poly(1,4-phenylene-2,6-benzobisthiazole) are described for both isotropic and nematic solutions. The data include both steady-state and transient behaviour. For isotropic solutions it is found that a single-integral constitutive equation (a form of the B.K.Z. equation) represents the data available. For nematic solutions unexplained behaviour is observed for small κ, perhaps related to unstable flow in simple shear predicted for such solutions by some mechanistic theories for the parameters in the Leslie–Erickson constitutive equation. For larger κ the flow behaviour may be represented by a modified form of the single-integral equation.