Synergistic effect enhanced shape recovery behavior of metal-4D printed shape memory polymer hybrid composites

Abstract The four-dimensional (4D) printing technology enables the convergence of three-dimensional (3D) printing and shape memory polymer (SMP). The aim of this research is to demonstrate the synergistic effect between a spring steel strip (SSS) and a 4D printed thermoplastic SMP on enhancing the shape recovery properties. The recovery time of the SMP/SSS hybrid composite was shortened by 39% as compared to that of the SMP specimen. The corresponding recovery force of the SMP/SSS hybrid specimen at 64 °C was 9 N, 199 times of that of the non-hybrid SMP specimen. For optimizing the design of hybrid composite specimens, the structural parameters, such as hybrid stacking configuration, SMP infill percentage and SSS thickness, have been also investigated and their influences on the shape recovery properties of the hybrid composite specimens have been identified. The present results signify a promising approach to improve the performance of SMP based sensors and actuators using hybrid composites.