A thermoviscoelastic model for the one-way and two-way shape memory effects of semi-crystalline polymers

Both one-way and two-way shape memory effects induced by crystallization and melting tran-sitions have been recently demonstrated in several semi-crystalline polymers. The paper proposes a novel thermoviscoelastic phase transition model accounting for the underlying mechanisms of the material. The nonlinear Adam-Gibbs model of structural relaxation and a modified Eying model of viscous flow are incorporated to characterize the thermomechanical behaviors of the amorphous phase. Another main feature of the model lies in the characterization of the formation and melting of the crystalline phase based on a theory of multiple natural configurations. Com-parisons with uniaxial shape memory experiments show that the model can well reproduce the stress-strain-temperature responses in different loading conditions.