Thermo-electro-mechanical characterization of a shape memory composite during electric activation

The present experimental research consists on the detailed thermo-electro-mechanical characterization of a nanocomposite with shape memory properties activated by an electric current. The SMC is functionalized polycaprolactone (PCL) doped with 3 wt% of multiwall carbon nanotubes (MWCNT). The PCL has a melting temperature of 43 °C at which the crystalline phase melts and the material becomes rubbery thanks to its covalent crosslinks. The SMC can be formed into its temporary shape, which will be kept when cooling down below its crystallization
temperature. The permanent shape can be recovered by heating up the SMC again above 43 °C. There are, however, very few reports on the strain dependence of the electrical resistance R of the SMC. In addition, the monitoring of the electrical properties of the SMC during the shape memory cycle has, to our knowledge, not yet been covered in spite of its vital importance for accurately and efficiently controlling the heating of the SMC with minimum electric power. Under an electric current, the precise temperature T depends on the resistance R of the SMC, the latter being in turn dependent on T and applied strain. Simultaneous monitoring of strain, stress, T and R
is carried out in the present work to better understand the interplay between mechanical, electrical,
and thermal properties of such SMC.