Shape memory effect (SME) of polymers is a property that concerns both, macroscopic and microscopic changes. The variation of internal polymer properties such, as molecular weight (Mw), rigidity, and viscoelasticity could alter its SME. In this study, a bi-parabolic model with six parameters is used to describe the viscoelastic behavior of a shape memory polymer (SMP) blend (40% poly(caprolactone), PCL/60% Styrene–Butadiene–Styrene) with different PCL Mw. These parameters are determined using the Cole–Cole method. Modeling curves (E″ = f (E′)) will be then compared to experimental data from dynamical mechanical analysis (DMA) tests. It is shown that the bi-parabolic model predicts well the behavior of the SMP mixture for different Mw of PCL. Afterwards, the evolution of the model parameters with the Mw of PCL is investigated. It is revealed that, when Mw of PCL drops, the relaxation modulus E0 increases. This result proves that the rigidity of the SMP blend rises with Mw declines