Relations between loss angles in isotropic linear viscoelastic materials

Starting from the relations between complex dynamic moduli simple diagrams are deduced connecting the locus of complex Poisson's ratiov* ≡v′ +iv″ in the complexv* plane with differences between various loss angles. From these diagrams the sequence of magnitudes of several loss angles appearing in linear viscoelastic theory is deduced. Although theoretically this sequence depends on the values ofv′ andv″, it is found experimentally that for polymeric materials, due to the fact that the values ofv′ andv″ are constrained to limited ranges, general rules can be given. The sequences deduced are compared with experimental data. Finally some relations are used to illustrate the phase relationships between stress and deformations in an uniaxial stress experiment. From these relations a new method for measuring the loss angle in compression is suggested.