Reversible plasticity shape memory effect in epoxy/CNT nanocomposites - A theoretical study

A theoretical investigation on the reversible plasticity shape memory (RPSM) properties of Multi-Walled Carbon Nanotubes (MWCNT) reinforced epoxy nanocomposites is presented. A typical RPSM cycle involves loading and stress relaxation below the glass transition temperature and unconstrained strain recovery above glass transition temperature. This paper attempts to study the underlying mechanisms by employing a thermo-visco-elastic model incorporating structural and stress relaxation mechanisms. The effective properties of the nanocomposites were determined from basic micro-mechanics models and standard thermo-mechanical experiments. The variations in model parameters between neat and filled epoxy were studied and the influence of MWCNT on the material behavior are discussed. The simulations agreed quite well with the experimental results for both neat and filled epoxy. The model was further able to capture the thermo-mechanical behavior under different programming conditions like strain rate, strain level and relaxation time.