Additive Manufacturing of Alumina‐Reinforced Elastomers

Vat photopolymerization (VPP) enables the fabrication of high‐resolution elastomeric components for soft robotic and functional applications; however, the limited mechanical robustness of printed elastomers restricts their structural applicability and long‐term durability. In this work, alumina‐reinforced elastomeric composites were fabricated via VPP by incorporating platelet‐shaped and sub‐micron alumina particles (3–9 wt%) into a commercial photocurable resin. The crystallographic texture of the fillers within the printed parts was quantified using the Lotgering factor (LF), enabling a comparative assessment of morphology‐dependent orientation. Platelet‐filled systems exhibited pronounced preferred orientation (LF up to ∼0.55) and lower porosity compared to sub‐micron systems (LF » 0), resulting in significant improvements in tensile performance. At 3 wt% platelet loading, the ultimate tensile strength increased from 12.4 to 45.7 MPa while fracture elongation nearly doubled relative to the neat resin. Cyclic testing further revealed enhanced strength retention at intermediate platelet loading. In contrast, sub‐micron alumina produced only moderate improvements due to limited orientation and higher defect sensitivity. The results demonstrate that filler morphology plays a decisive role in governing consolidation, orientation, and mechanical response in elastomeric VPP composites.