Modeling the multiple shape memory effect and temperature memory effect in amorphous polymers
Amorphous polymers achieve a shape memory effect from the tremendous change of chain mobility in the glass transition. The span of the glass transition region has a direct influence on the shape recovery behavior. In this paper, we investigated the shape memory behavior of Nafion, which has an extremely broad glass transition region. We measured the influence of the shape memory programming temperature on the recovery response and multiple shape memory effect. We applied a finite deformation, nonlinear viscoelastic model with a discrete spectrum of relaxation times to describe the shape memory behavior of the material. The parameters of the relaxation spectrum were determined from the master curve of the relaxation modulus. The model was implemented for finite element analysis and applied to design a multiple switchable pattern transformation of a Nafion membrane.