抄録
To express the linear viscoelastic properties of plastics, the author proposes the use of new spectra, G1(τ) and F1(τ) defined by Eqs. 4 and 7 as substitutes for the retardation and relaxation spectra, F(τ) and F(τ). These new spectra, implying the viscosity term and not being normalized, little differ from the Schwarzl-Staverman's 1st approximation for F(τ), F(τ) derived from creep and relaxation functions. The author attaches importance to the G1(τ) and F1(τ) as the functions expressing the nature of plastics in stead of treating them only as the derivatives from the 1st approximations for F(τ) and F(τ).
As given in Eqs. 3, 4, 6, 7 and 9, the computings of these new spectra from the data of creep, relaxation and constant strain rate tensile tests are carried out exactly and easily, and the reverse is the same. The transformation between G1(τ) and F1(τ) is also very easily carried out by Eq. 10 using the electronic computer. The fact that not every continuous function arbitrarily given for the creep or relaxation curves can be expressed by F(τ) or F(τ), but that they can always, be expressed by G1(τ) or F1(τ) is a distinguished feature of using these new spectra, apart from the discussion whether the feature is necessary for the description of the nature of plastics or not.
The derivations of viscoelastic relations expressed by G1(τ) and F1(τ), the discussion on the benefits of using these spectra and the examples of G1(τ)&F1(τ) transformations are given below.
