Epoxy chain extender compatibilized poly(lactic acid)/polyoxymethylene blends: Improved crystallization, enhanced heat resistance and toughness for three-dimensional printing.

Bio-based and biodegradable poly(lactic acid) (PLA) is severely limited in three-dimensional (3D) printing due to its inherent brittleness, poor heat resistance, and slow crystallization rate. In this study, PLA/polyoxymethylene (POM) composites were prepared via one-step melt blending with an epoxy-functionalized oligomer (ADR) as compatibilizer. The regulatory effects and mechanisms of ADR on the crystallization behavior, morphology, rheological properties, mechanical performance, heat resistance, and optical transparency of the system were systematically investigated. In-situ FTIR results verified that ADR strengthened interfacial hydrogen bonding and molecular chain entanglement between PLA and POM through in-situ chain extension/branching reactions, which effectively promoted the heterogeneous nucleation of PLA by POM and enabling PLA to form well-developed crystal structures during cooling. Among the as-prepared blends, PLA/POM/ADR1.5 exhibited the optimal comprehensive properties: compared with neat PLA, its tensile strength was maintained at a high level of 59.1 MPa, while the elongation at break increased significantly from 6.0% to 111.2%, achieving a transition from brittle to ductile fracture; the VST increased significantly from 63 °C of neat PLA to 154 °C, and the transmittance at 450 nm remained above 82%. Fused deposition modeling (FDM) 3D printing validation demonstrated that printed products from this filament showed no obvious deformation after heat treatment at 110 °C for 10 min, exhibiting excellent heat resistance. This study provides a simple and efficient strategy for developing high-performance PLA-based filaments with balanced toughness, heat resistance, and transparency for 3D printing applications.