Shape memory behavior of polyacrylate-based amorphous nanocomposite hydrogel under uniaxial tension: Modeling and experimental

In the present work, a comprehensive constitutive equation was developed to predict the shape memory behavior of amorphous nanocomposite hydrogel systems. The effects of interfaces of nanoparticles and micro-vessels of water with polymeric matrix and their thermal and physicomechanical properties on the model prediction were considered. An amorphous polyacrylate-based hydrogel with the glass transition temperature as a switching temperature was selected. Nanocomposite hydrogels containing 0.2 and 1.2 wt% of multiwall carbon nanotubes were prepared. The accuracy of the proposed model was evaluated with experimental data for all the selected systems. The dynamic mechanical analysis results of the shape memory behavior showed the presence of nanoparticles increased the shape fixing ratio and the rate of shape recovery of polyacrylamide nanocomposite hydrogels. The model prediction of shape recovery ratio in all systems was 100%. A comparison of the model prediction with the shape memory experimental data revealed a good agreement.