Manipulation of Printing Direction and Temperature on the Mechanical Properties and Shape Recovery of Thermoplastic Polyurethane 4D-Printed Polymer-Textile Composites

In recent years, textile practitioners have utilized polyurethane (PU) SMPs to develop 4D printed polymer-textile composites (4DP PTCs) which have distinct mechanical properties. However, little attention has been paid to combining the effects of extrusion direction and temperature of individual polymer layers on the mechanical properties and shape performance of 4DP PTCs. Hence this study explores the effects of such conditions through the development of thermo-responsive 4DP PTCs composed of thermoplastic polyurethane (TPU) with a Shore hardness of 70A and 82A, respectively, PU SMP, and a nylon substrate. This study finds that the mechanical and shape performance of 4DP PTCs can be manipulated via varying the extrusion temperature and direction. Weft direction specimens showed greater stiffness (0.19 GPa) and shape fixity (up to 99.56%) whilst warp showed higher flexibility (0.10 GPa) and better shape recovery (up to 96.58%). Hence, 4DP PTCs can be selectively stiffened for applications that is, pressure suits and soft robotics that require enhanced stiffness in specific direction of movement, enabling further development of shape shifting textiles with complex surfaces and structures.