Abstract
The 1st., 2nd. and 3rd. approximations to the relaxation (and retardation) spectrum from the relaxation modulus (and creep compliance) without differentiation were obtained on the same basis as in those from the complex modulus reported previously (J. Colloid Sci., 14, 36 (1959)).
Several values of relaxation modulus equally spaced on the logarithmic time scale are used to give those approximations and the 3rd. approximation to the relaxation spectrum, H3 is written in the form,
H3(lnθ) =[α3/(α2-1)(α-1)lnα]×{G(t)-[(α2+α+1)/α2]G(αt)+[(α2+α+1)/α3]G(α2t)-(1/α3)G(α3t)}|t=θX3(α)
Here θ represents the relaxation time and X3(α) is the root of Eq. (23) in the text. α is an arbitrary valued parameter but a value of 0.20 is suggested for log α in actual use.
