Rheology of a viscoelastic emulsion with a liquid crystalline polymer dispersed phase

The steady-shear viscosity and first normal stress difference and the dynam ic storage and loss moduli have been measured for a blend consisting of a t hermotropic liquid crystalline polymer dispersed in a thermoplastic fluorop olymer matrix. The components are immiscible and nonreacting. Consistency w ith the Palieme emulsion theory for viscoelastic blends is possible if and only if the interfacial tension contribution is negligible for droplets tha t are comparable in size to a liquid crystalline domain or smaller, while r etaining the effect for larger droplets. Steady shear results are approxima tely described by the scaling of the Doi-Ohta theory, but there is a signif icant reduction in the excess shear stress over a finite shear-rate range f or the lowest concentration, which contains the smallest droplets. (C) 1999 The Society of Rheology. [S0148-6055(99)02006-4].