FRACTIONAL CALCULUS DESCRIPTION OF DMTA TRANSIENT IN LONG-MEMORY MATERIALS

Fractional calculus descriptions of polymer viscoelasticity are becoming increasingly popular, because they allow a concise description of non-Debye relaxation and memory of strain history using a small number of parameters. However, use of fractional calculus to this end is frequently restricted to description of dynamic behaviour, such as in dynamic mechanical thermal analysis (DMTA), where the dependence of the complex modulus on frequency can be expressed algebraically in closed form. However, this approach is only valid in the steady state. The problem of the approach to steady state and of the effect of the slowly-decaying transient on DMTA measurements is addressed here.