Viscoelastic, Shape Memory, and Fracture Characteristics of 3D Printed Photosensitive Epoxy-Based Resin Under the Effect of Hydrothermal Ageing

The use of 3D printed polymers and their composites as shape memory materials in various smart engineering applications has raised the demand for such functionally graded sustainable materials. This study aims to investigate the viscoelastic, shape memory, and fracture toughness properties of the epoxy-based ultraviolet (UV)-curable resin. A UV-based DLP (Digital Light Processing) printer was employed for the 3D printing (3DPg) epoxy-based structures. The effect of the hydrothermal accelerating ageing on the various properties of the 3D printed (3DPd) components was examined. The viscoelastic performance in terms of storage modulus, loss modulus, and glass transition temperature (Tg) was evaluated. The shape memory behaviour in terms of shape fixity and shape recovery results were determined using dynamic mechanical thermal analysis (DMTA). DMTA is used to reveal the molecular mobility performance through three different regions, i.e., glass region, glass transition region, and rubbery region. The shape-changing region (Within the glass transition region) between the Tg value from the loss modulus and the Tg value from the tan delta was analysed. The temperature-memory behaviour was investigated for flat and circular 3DPd structures to achieve sequential deployment. The critical stress intensity factor values of the single-edge notch bending (SENB) specimens have been explored for different crack inclination angles to investigate mode I (opening) and mixed-mode I/III (Opening and tearing) fracture toughness. This investigation study can be employed to create highly complex shape memory 3DPd durable structures that can be reconfigured multiple times under large deformation.