4D printed continuous fiber reinforced shape memory polymer composites with enhanced mechanical properties and shape memory effects

Multi-material four-dimensional (4D) printing has gathered significant interest among researchers as an emerging manufacturing technique. In this study, continuous carbon fibers are integrated into shape memory polymers (SMPs) using multi-material co-extrusion 4D printing. This process results in the creation of shape memory polymer composites (SMPCs) characterized by high load-bearing capacity and stimulus responsiveness. Micro-CT scanning is employed to evaluate the internal porosity of SMPCs, based on which the three-dimensional (3D) reconstruction images are generated. Meanwhile, various mechanical tests are implemented, including tensile, three-point bending, and compression tests, to explore the mechanical properties and fracture modes of the 4D printed SMPCs. In addition, the shape memory effect of the 4D printed SMPCs is verified by experiments and finite element simulations. The results demonstrate shape recovery rates higher than 96%. This study offers valuable insights into the fabrication and testing of smart composites with compatible deformation and high load-bearing capacity.