4D printing and programming of continuous fibre-reinforced shape memory polymer composites

This study demonstrates the use of fused filament fabrication (FFF) 4D printing (4DP) to print programmable continuous fibre-reinforced composite (CFRC) structures with exceptional strength and eco-friendly features. This research focuses on bio-shape memory polymer composites (SMPCs) and employs experiments to fabricate lightweight CFRC parts using FFF technology. Different types of continuous fibres, including carbon fibre (CF), aramid fibre (AF), and fibreglass (FG), are incorporated into a biopolymer matrix made of biodegradable polylactic acid (PLA). The study evaluates microstructure, mechanical properties, and shape memory properties of SMPCs, employing techniques like cold and hot programming. Continuous fibres significantly enhance mechanical properties, increasing strength by over 1027.5 % in tensile tests and nearly 497.3 % in three-point bending tests. The research also addresses shape recovery and fixity ratios in 4D-printed SMPCs, finding a decrease when continuous fibres are incorporated into PLA. Notably, FGPLA specimens achieve the highest shape recovery ratio of approximately 95 +/- 1 % after pure PLA. These findings highlight the potential of 4D-printed CFRCs in various applications, from human-material interaction to mechanical and biomedical fields. They contribute to sustainability by reducing material consumption and waste, demonstrated through the creation of reusable and lightweight items like hooks, lockers, finger splints, and meta-composites.