A viscoelastic material also possesses a complex dynamic viscosity, tj = v( + it] , and it can be shown that rf = G /ioj v( = G" ju) and rf" = G fu)y where (0 is the angular frequency. The parameter T is useful for many viscoelastic fluids in that a plot of its absolute value T vs angular frequency in radians/s is often numerically similar to a plot of shear viscosity T vs shear rate. This correspondence is known as the Cox-Merz empirical relationship. The parameter T is called the dynamic viscosity and is related to G , the loss modulus the parameter V " does not deal with viscosity, but is a measure of elasticity. [Pg.178]

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