Preparation and properties of CaCO3/PEG/PLA shape memory composites

Purpose For the poly (ethylene glycol)/poly (lactic acid) (PEG/PLA) blend system, plasticization-driven toughening sacrifices modulus and load bearing capacity, creating a critical strength toughness trade-off. Few reports resolve this issue using low-cost commercial micron-sized inorganic fillers coupled with melt-shear in-situ fragmentation for PEG/PLA shape-memory systems. This study aims to develop a high-rigidity, high-toughness bio-based composite capable of rapid thermal response, simultaneously fulfilling high load-bearing requirements and high-sensitivity actuation. Design/methodology/approach CaCO3/PEG/PLA (CPP) composites were fabricated via melt blending and hot-pressing. The effects of CaCO3 size on thermal stability, mechanical property and shape memory performance at 80 °C were systematically investigated. Findings The CPP composites exhibit distinct mechanical-shape-memory trade-offs with varying filler loadings. Sample P1 (0.5 wt% 1250-mesh CaCO3) achieves balanced performance: yield strength (27.04 MPa, + 32.3%) and tensile modulus (718.01 MPa, + 34.8%) versus neat PEG/PLA, alongside 141.78% elongation at break and full shape-recovery (Rr = 100%). In comparison, high-loading Sample P4 achieves superior mechanical properties (32.25 MPa yield strength, + 57.8%; 921.98 MPa tensile modulus, + 73.1%; elongation at break 259.60%), yet its shape-recovery ratio drops sharply to 51.43% despite retaining high shape-memory fixity ratio (Rf). All CPP composites exhibited ultrafast thermo-response: reaching 25% recovery within 40 s at 80 °C with Rf > 90%. Research limitations/implications This study is limited to CaCO3 as filler and 80 °C triggering conditions. While demonstrating ultrafast response, the specific mechanism behind the rapid recovery requires further theoretical investigation. Future work should explore other bio-based fillers or trigger temperatures to broaden the material system and enhance fundamental understanding. Practical implications The CPP composites offer significant practical value, combining high strength, toughness and rapid shape recovery. They are ideal for applications requiring immediate response, such as smart packaging shrink bands, temperature-controlled fasteners and quick-release devices, effectively bridging the gap between load-bearing capacity and dynamic actuation. Social implications This research promotes the development of sustainable, bio-based smart materials, reducing reliance on petroleum-based plastics. By enabling efficient, low-energy responsive systems, it contributes to environmental protection and supports the advancement of green technologies in consumer products and industrial applications. Originality/value This work demonstrates that simple melt processing of commercial micron-CaCO3 balances rigidity, toughness and fast thermos-responsive shape memory. The fast-responding CPP composites provide new references for bio-based smart materials such as smart packaging shrink bands and temperature-controlled fasteners.