Thermo-Mechanical Modeling of Layered Shape Memory Polymers

Thermo-Mechanical Modeling of Layered Shape Memory Polymers

Student: Karson Leperi, University of South Carolina

Mentor: Dr. Jiang Du

PI: Dr. Eric Baer

                In this work, a thermo-mechanical model was created to predict the shape memory behavior of microlayered polymers. A three-element viscoelastic equation was used to model the memory layer, while two Mooney-Rivlin hyperelastic equations were used to model the switching layer. One of the Mooney-Rivlin equations represented the melted phase of the switching layer which occurred above the transition temperature and the other represented the solid phase of the switching layer which occurred below the transition temperature. The total stress and strain were calculated by combining these three equations, along with variables representing the volume fraction of each phase of the switching layer and an equation representing non-mechanical stress in the system. The model was validated by comparing the fitting results to the experimental data of a 50/50 microlayered polyurethane (PU) / polycaprolactone (PCL) strand, with good agreement between them. This work is unique in that this is the first attempt to model the shape memory behavior of microlayered polymers. Most of the previous works into thermo-mechanical modeling have only focused on block co-polymers.