RELATION BETWEEN VISCOELASTICITY AND SHEAR-THINNING BEHAVIOR IN LIQUIDS

The shear-thinning behaviour of a liquid is represented in terms of a relaxation time λ, defined by the ratio η0/G0 of initial viscous and elastic constants. The relationship provides a very simple basis for the evaluation of λ and G0 from viscosity/shear data. Results are compared with relaxation times and moduli from primary normal-stress measurement, from stress relaxation and from direct measurement of recoverable shear strain. Good agreement is found but there is experimental evidence the recoverable shear strain γe is related to normal stress N1 and shear stress σ by γe = N1/3σ, which does not agree with the theoretical prediction of either Weissenberg or Lodge. © 1979 Dr. Dietrich Steinkopff Verlag.