Bio‐Based Citric Acid‐Cured Epoxy Shape Memory Composites: Effect of Mineral Fillers on Thermal and Shape Memory Performance

ABSTRACT The development of sustainable thermosetting polymers with thermo‐responsive shape memory capability has attracted increasing attention due to their potential applications in smart materials and advanced engineering systems. In this study, bio‐based citric acid was employed as an alternative curing agent for epoxy resin to fabricate thermo‐responsive shape memory epoxy composites. The thermal properties, as well as shape memory behavior of the composites were investigated by differential scanning calorimetry (DSC) analysis and bending tests, respectively. The effects of polyethylene glycol (PEG) as a plasticizing agent in addition to sepiolite and colemanite as mineral reinforcing fillers on the thermal and shape memory properties of the epoxy composites were systematically investigated. The incorporation of PEG improved the chain mobility of the epoxy network, enabling decreased T g and enhanced shape recovery behavior. The optimized composites exhibited excellent thermo‐responsive shape memory performance, achieving high shape recovery ratios with rapid recovery response under thermal stimulation. The obtained results demonstrate that citric acid‐cured epoxy composites reinforced with natural mineral fillers provide a promising sustainable platform for the development of high‐performance shape memory materials.