In this work, a newly prepared cationic/free-radical photopolymer, which consists of two epoxies and a tetrafunctional acrylate, is presented for the first time for a visible light stereolithography (SL), showing the advantages of both cationic and free-radical resins. An onium salt, commonly used as a cationic UV initiator, and a photosensitizer make the blend suitable for a near-visible (405 nm) SL. An increase in the polymerization rate and a drop in the induction period are observed for the newly prepared cationic/free-radical blend, compared with either only cationic systems or free-radical resins. This suggests that the combination of cationic and free-radical polymerizations in a single resin has a positive synergistic effect. The addition of silica nanoparticles to the blend provides a reinforcing and toughening effect. Indeed, the resin loaded with silica shows a 31% increase in the elastic modulus, compared with the unfilled resin. Regarding the values of tensile strength and elongation at break, they, respectively, grow by 47 and 15%, when the nanocomposite resin is compared with the neat resin. A very low volumetric shrinkage of 0.7% and a remarkable printing quality of objects obtained with this new photopolymer will enable the 3D printing of microrobots, bioengineering microdevices, and sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48333.
Near-visible stereolithography of a low shrinkage cationic/free-radical photopolymer blend and its nanocomposite
Suriano R.;Turri S.;Levi M.
2020-01-01
Abstract
In this work, a newly prepared cationic/free-radical photopolymer, which consists of two epoxies and a tetrafunctional acrylate, is presented for the first time for a visible light stereolithography (SL), showing the advantages of both cationic and free-radical resins. An onium salt, commonly used as a cationic UV initiator, and a photosensitizer make the blend suitable for a near-visible (405 nm) SL. An increase in the polymerization rate and a drop in the induction period are observed for the newly prepared cationic/free-radical blend, compared with either only cationic systems or free-radical resins. This suggests that the combination of cationic and free-radical polymerizations in a single resin has a positive synergistic effect. The addition of silica nanoparticles to the blend provides a reinforcing and toughening effect. Indeed, the resin loaded with silica shows a 31% increase in the elastic modulus, compared with the unfilled resin. Regarding the values of tensile strength and elongation at break, they, respectively, grow by 47 and 15%, when the nanocomposite resin is compared with the neat resin. A very low volumetric shrinkage of 0.7% and a remarkable printing quality of objects obtained with this new photopolymer will enable the 3D printing of microrobots, bioengineering microdevices, and sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48333.File | Dimensione | Formato | |
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Invernizzi_Near-visible stereolithography of a low shrinkage cationic free-radical photopolymer blend and its nanocomposite_J Appl Polym Sci_2019.pdf
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