Enhancing stiffness and strength in SLA-printed photopolymer composites through UV post-curing and thermal annealing

Abstract

This study examines the influence of printing parameters and post-processing on the mechanical performance of SLA-printed acrylate-based materials. Specimens were fabricated at two printing speeds (100 mm/s, 130 mm/s) and three layer thicknesses (0.05–0.15 mm), followed by UV post-curing and thermal annealing (70–90°C). Tensile and Shore D hardness tests revealed that lower speeds and thinner layers improved initial stiffness and strength due to enhanced interlayer bonding. UV post-curing significantly increased surface rigidity, particularly in high-speed prints with insufficient initial polymerization. Optimal mechanical performance was achieved at 80°C, where thermal relaxation and UV-induced crosslinking synergized. However, excessive annealing at 90°C degraded polymer chains, reducing mechanical integrity. While UV curing improved modulus and hardness, it could not fully recover tensile strength in high-speed prints, likely due to interfacial weaknesses. These findings underscore the critical interplay between print parameters and post-processing, offering a strategy to enhance mechanical reliability in SLA-manufactured parts.