Thermal shock durability of material extrusion-fabricated oyster shell-filled PLA for applications in extreme environments

초록

Material extrusion (MEX) has attracted increasing attention for additive manufacturing in extreme environments. In this study, the thermal shock durability of MEX-fabricated (MEXed) oyster shell-filled PLA was evaluated after 100 thermal shock cycles between −30 °C and 85 °C. The dimensional changes remained below 4%, although anisotropic deformation dependent on the filament deposition direction was observed. Thermal shock caused only minor reductions in tensile strength (0.8% and 5.7% for the longitudinal and transverse specimens, respectively), whereas the elongation at break decreased by 19.0% and 16.5%, accompanied by the disappearance of the yielding behavior. SEM observations revealed a smoother fracture surface after thermal shock while maintaining nearly identical porosity (∼3.7%). In addition, the melting enthalpy approximately doubled after thermal shock, indicating increased crystallinity, which explains the reduced ductility and more brittle fracture behavior. These findings demonstrate that MEXed oyster shell-filled PLA maintains excellent dimensional stability and tensile strength under repeated thermal shock despite reduced ductility, providing useful insight into the development of sustainable MEX feedstocks for additive manufacturing in extreme thermal environments. © 2026 The Author(s).

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