Influence of temporal irradiance profiles and printing temperature on green-body mechanical properties and interfacial separation forces in LCD-based vat photopolymerization.
basic_science · Level V
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- Record sourced from PubMed, PMID 42594412.
- Also identified by DOI 10.1016/j.jmbbm.2026.107599.
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Abstract
To investigate whether printing temperature and the temporal distribution of irradiance during LCD-based vat photopolymerization influence the mechanical properties and interfacial behavior of printed photopolymer green bodies when the total radiant exposure is kept constant. A modified LCD-printer equipped with a programmable LED illumination system enabling temporal irradiance modulation and integrated load-cell monitoring was used to fabricate green-body tensile specimens (N = 175) from a dental model resin. Specimens were printed at 22°C and 40°C using constant, linearly increasing, and linearly decreasing irradiance profiles with identical total radiant exposure. Elastic modulus (EM), fracture energy (FE), ultimate tensile strength (UTS), strain at break (SB), and separation force (SF) were determined before post-curing. Fracture surfaces were evaluated macroscopically and microscopically. Mechanical properties were analyzed using two/one-way ANOVA and Scheffé post-hoc testing (α = 0.05), whereas SF was evaluated descriptively. Printing temperature significantly affected all investigated mechanical properties (p < 0.001). Irradiance profile significantly influenced EM, FE, UTS, and SB, whereas significant temperature × irradiance interactions were observed for EM, UTS, and SB. Across both temperatures, the constant irradiance profile generally resulted in the highest values for the investigated mechanical properties, whereas the decreasing irradiance profile resulted in the lowest values. In contrast, decreasing irradiance consistently reduced SF compared with constant and increasing irradiance profiles. Fracture surface analysis revealed no systematic morphological differences between the investigated groups. Temporal irradiance modulation represents an additional process parameter in LCD-based vat polymerization. Although it exerted only a limited influence on the investigated mechanical properties of green bodies, decreasing irradiance consistently reduced SF, indicating that the temporal distribution of radiant exposure affects interfacial behavior during layer formation. These findings may contribute to the further optimization of exposure strategies in LCD-based vat photopolymerization.