Viscoelastic and ultrasonic relaxation in di-(2-ethylhexyl) phthalate

Abstract

Measurements have been made of the viscosity, density, shear resistance and the velocity of propagation and attenuation of longitudinal waves for di-(2-ethylhexyl) phthalate. The relaxational behaviour in shear is the same as that found for many other liquids and is described in terms of the complex shear modulus as G*=[1/G_∞+ 1/jωη+ 2/(jωηG_∞)^½]^–1. The compressional relaxation is described by a similar equation, apart from a small discrepancy at low values of ωη/G_∞. The relaxing part K₂ of the compressional modulus is equal to the limiting shear modulus G_∞ and the compressional viscosity ηv is 3 times the shear viscosity η.