The influence of particle size distribution on the curing behavior of ceramic-filled resins for vat photopolymerization

Abstract

Optimizing the process of vat photopolymerization for ceramics necessitates the thorough understanding of the complex interactions between light and ceramic particles. However, it is not yet fully described how the size distribution of ceramic particles affects the curing behavior of ceramic-filled resins. Thus, this contribution provides insight into the influence of the particle size distribution (PSD) on the rheological behavior and the polymerization kinetics of photo-curable ceramic-filled resins. Four grades of alpha-aluminum oxide with different PSDs in an acrylate-based photo-curable resin were investigated. The PSD was measured using a laser diffraction particle size analyzer based on the Mie theory. The quantum of attenuated light was measured with an Ultraviolet/Visible (UV/Vis) spectrophotometer equipped with a modified integrating sphere accessory. UV/Vis measurements revealed that samples with a smaller mean particle size result in larger attenuation in the UV region of the spectrum (i.e., ∼190 nm–420 nm). Moreover, photo-rheology measurements revealed that larger particles generally result in faster polymerization rates without a noticeable change in the degree of conversion. In addition, rheological and sedimentation tests revealed that ceramic-filled resins with a larger mean particle size exhibit lower viscosity and lower sedimentation stability. The findings of this work contribute to the optimization of the process of ceramic powder selection. This results in an increase in the sedimentation stability of ceramic-filled resins, and a customization of their curing behavior.