Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy

The degree of mechanical anisotropy in objects printed with laser vat photopolymerization (VPP) remains controversial. It has been stated that objects with a higher degree of mechanical isotropy are produced with VPP as compared to other polymer-based additive manufacturing techniques, such as fused...

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Main Authors: Dagoberto Torres-Alvarez, Angel Celis-Guzman, Alan Aguirre-Soto
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Additive Manufacturing Letters
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Online Access:http://www.sciencedirect.com/science/article/pii/S2772369024000720
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author Dagoberto Torres-Alvarez
Angel Celis-Guzman
Alan Aguirre-Soto
author_facet Dagoberto Torres-Alvarez
Angel Celis-Guzman
Alan Aguirre-Soto
author_sort Dagoberto Torres-Alvarez
collection DOAJ
description The degree of mechanical anisotropy in objects printed with laser vat photopolymerization (VPP) remains controversial. It has been stated that objects with a higher degree of mechanical isotropy are produced with VPP as compared to other polymer-based additive manufacturing techniques, such as fused filament fabrication (FFF). However, reports on the evaluation of resin-dependency of the mechanical anisotropy obtained with VPP are scarce. Furthermore, the degree of anisotropy (DA) was quantified using different procedures. Here, six commercial resins were selected to evaluate how the DA correlates to the initial rate of polymerization (RP0), critical energy (EC), and penetration depth (DP) for materials with a broader range of properties. State-of-the-art procedures to calculate the degree of mechanical anisotropy are discussed, and an ideal method is proposed, namely, the ratio of the standard deviations related to the inter- and intra-layer forces: DA=(sdinter/sdintra). The elastic modulus (E) was confirmed isotropic with the three resins that were previously reported. However, objects printed with the additional resins that polymerize at higher initial rates (RP0 =72.1 mM/s) and with lower critical energies (EC = 0.36 mJ/cm2) appear more anisotropic. A linear trend was obtained for the scaling of the mechanical DA with RP0. Moreover, a logarithmic correlation between EC and the DA in E was found, which appears inappropriate for EC as a function of the DA in the maximum stress (σMax). This study aims to spur research on the mechanisms underlying the dependence of the mechanical DA on the resin-curing behavior for objects fabricated by VPP.
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spelling doaj-art-f4d8074f2a224e1fb313f2f202b40f042025-01-17T04:52:28ZengElsevierAdditive Manufacturing Letters2772-36902025-02-0112100264Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energyDagoberto Torres-Alvarez0Angel Celis-Guzman1Alan Aguirre-Soto2School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, NL, MexicoSchool of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, NL, MexicoCorresponding author.; School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, NL, MexicoThe degree of mechanical anisotropy in objects printed with laser vat photopolymerization (VPP) remains controversial. It has been stated that objects with a higher degree of mechanical isotropy are produced with VPP as compared to other polymer-based additive manufacturing techniques, such as fused filament fabrication (FFF). However, reports on the evaluation of resin-dependency of the mechanical anisotropy obtained with VPP are scarce. Furthermore, the degree of anisotropy (DA) was quantified using different procedures. Here, six commercial resins were selected to evaluate how the DA correlates to the initial rate of polymerization (RP0), critical energy (EC), and penetration depth (DP) for materials with a broader range of properties. State-of-the-art procedures to calculate the degree of mechanical anisotropy are discussed, and an ideal method is proposed, namely, the ratio of the standard deviations related to the inter- and intra-layer forces: DA=(sdinter/sdintra). The elastic modulus (E) was confirmed isotropic with the three resins that were previously reported. However, objects printed with the additional resins that polymerize at higher initial rates (RP0 =72.1 mM/s) and with lower critical energies (EC = 0.36 mJ/cm2) appear more anisotropic. A linear trend was obtained for the scaling of the mechanical DA with RP0. Moreover, a logarithmic correlation between EC and the DA in E was found, which appears inappropriate for EC as a function of the DA in the maximum stress (σMax). This study aims to spur research on the mechanisms underlying the dependence of the mechanical DA on the resin-curing behavior for objects fabricated by VPP.http://www.sciencedirect.com/science/article/pii/S2772369024000720Critical energyLaser vat photopolymerizationMechanical anisotropyPolymerization kineticsResin-dependent
spellingShingle Dagoberto Torres-Alvarez
Angel Celis-Guzman
Alan Aguirre-Soto
Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
Additive Manufacturing Letters
Critical energy
Laser vat photopolymerization
Mechanical anisotropy
Polymerization kinetics
Resin-dependent
title Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
title_full Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
title_fullStr Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
title_full_unstemmed Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
title_short Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
title_sort resin dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy
topic Critical energy
Laser vat photopolymerization
Mechanical anisotropy
Polymerization kinetics
Resin-dependent
url http://www.sciencedirect.com/science/article/pii/S2772369024000720
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AT angelcelisguzman resindependentmechanicalanisotropyinlaservatphotopolymerizationcorrelatestotheinitialrateofpolymerizationandcriticalenergy
AT alanaguirresoto resindependentmechanicalanisotropyinlaservatphotopolymerizationcorrelatestotheinitialrateofpolymerizationandcriticalenergy