Thermoelectrical Memory of Polymer Nanocomposites

The inclusion of nanoparticles improves the behavior of shape-memory polymers and allows new functionalities. It is shown in the present work that polyamide fibers loaded with carbon nanotubes (CNTs) exhibit novel memory functions associated to their electrical conductivity. Similar to classical shape memory polymers, the materials are predeformed at high temperature and then quenched down to room temperature and subsequently reheated. Their resistivity is recorded during the process and is found to decrease with temperature during the last heating stage. The rate of resistivity decrease exhibits a well-defined maximum at the temperature of predeformation. This unique response clearly shows an accurate thermoelectrical material memory. Temperature memory extended to electrical properties could serve for future sensing applications coupled to shape changes.