Tan delta

The tangent of the phase angle (= delta) of the sample.

Similar to phase angle this it is a relative measure of the viscous and elastic properties of a material.

It ranges from 0 for a fully elastic material to infinity for a fully viscous material, with a value of 1 where the storage modulus = loss modulus (see Cross over).

Technically, it is the ratio of the loss modulus over the storage modulus, and hence indicates the tendency of a material to dissipate energy (i.e., more viscous-like) or to store energy (i.e., more elastic-like).

Tan δ = G''/G' 

Related Methods