Characterizing UV Resin Curing With Additives Under Simulated Microgravity for In-Space Manufacturing

In-space manufacturing requires materials that can cure and perform reliably under microgravity, where heat transfer and solidification differ from terrestrial conditions. Containerless curing using acoustic levitation mimics these conditions partly by eliminating container (mold) constraints, which may lead to more uniform particle-polymer systems and consequently more uniform residual stress. This study investigates how curing environments influence the optical mechanical behaviour of photopolymer-alumina composites designed for space applications. Photoluminescence (PL) spectroscopy was used to observe characteristic spectral peak shifts in 15 vol% alumina nanocomposites under uniaxial compression. Samples were prepared using container curing via a mold and containerless curing through dual-axis acoustic levitation. Both curing methods produced a mix of positive and negative PL stress slopes; however, the containerless samples exhibited higher peak-shift magnitudes with increasing compressive stress, indicating greater piezospectroscopic sensitivity. The mold-cured beads showed higher stiffness and generally smaller PL slope magnitudes, corresponding with more pronounced particle agglomeration and sedimentation shown in microstructural images. Both curing conditions resulted in heterogeneous particle distributions, although the form and degree of clustering differed based on their curing processes. The findings indicate that the curing environment affects stress transfer, particle arrangement, and resulting photoluminescent response in alumina-filled composites, which is crucial for the development of functional stress-sensitive materials for in space manufacturing.