Shape memory behavior of PET foams

Shape memory properties of PET (polyethylene-terephthalate) foams have been evaluated for two different foam densities. Samples were subjected to multiple memory-recovery cycles along three different directions to measure the effect of foam anisotropy on static mechanical and shape memory properties. The memory cycle was performed by uniaxial compression tests at room temperature. Despite these severe conditions, PET foams demonstrated very good shape memory behavior with shape recovery always higher than 90%. Due to cycling, the mechanical performance of foam samples is partially reduced, mainly along the extrusion direction of the foam panels. Despite this loss of static performance, shape memory properties are only partially affected by thermo-mechanical cycles. The maximum reduction is 10% for shape fixity and 3% for shape recovery. The experimental results are particularly interesting considering that compression tests were undertaken at room temperature. Indeed, PET foams seem to be optimal candidates for self-repairing structures.