Academic literature on the topic 'Vat photopolymerization'
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Journal articles on the topic "Vat photopolymerization"
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Li, Xiangjia, and Yong Chen. "Vat-Photopolymerization-Based Ceramic Manufacturing." Journal of Materials Engineering and Performance 30, no. 7 (July 2021): 4819–36. http://dx.doi.org/10.1007/s11665-021-05920-z.
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Shaukat, Usman, Elisabeth Rossegger, and Sandra Schlögl. "A Review of Multi-Material 3D Printing of Functional Materials via Vat Photopolymerization." Polymers 14, no. 12 (June 16, 2022): 2449. http://dx.doi.org/10.3390/polym14122449.
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Additive manufacturing or 3D printing of materials is a prominent process technology which involves the fabrication of materials layer-by-layer or point-by-point in a subsequent manner. With recent advancements in additive manufacturing, the technology has excited a great potential for extension of simple designs to complex multi-material geometries. Vat photopolymerization is a subdivision of additive manufacturing which possesses many attractive features, including excellent printing resolution, high dimensional accuracy, low-cost manufacturing, and the ability to spatially control the material properties. However, the technology is currently limited by design strategies, material chemistries, and equipment limitations. This review aims to provide readers with a comprehensive comparison of different additive manufacturing technologies along with detailed knowledge on advances in multi-material vat photopolymerization technologies. Furthermore, we describe popular material chemistries both from the past and more recently, along with future prospects to address the material-related limitations of vat photopolymerization. Examples of the impressive multi-material capabilities inspired by nature which are applicable today in multiple areas of life are briefly presented in the applications section. Finally, we describe our point of view on the future prospects of 3D printed multi-material structures as well as on the way forward towards promising further advancements in vat photopolymerization.
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Rieger, Thomas, Tim Schubert, Julian Schurr, Andreas Kopp, Michael Schwenkel, Dirk Sellmer, Alexander Wolff, Juliane Meese-Marktscheffel, Timo Bernthaler, and Gerhard Schneider. "Vat Photopolymerization of Cemented Carbide Specimen." Materials 14, no. 24 (December 11, 2021): 7631. http://dx.doi.org/10.3390/ma14247631.
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Numerous studies show that vat photopolymerization enables near-net-shape printing of ceramics and plastics with complex geometries. In this study, vat photopolymerization was investigated for cemented carbide specimens. Custom-developed photosensitive WC-12 Co (wt%) slurries were used for printing green bodies. The samples were examined for defects using quantitative microstructure analysis. A thermogravimetric analysis was performed to develop a debinding program for the green bodies. After sintering, the microstructure and surface roughness were evaluated. As mechanical parameters, Vickers hardness and Palmqvist fracture toughness were considered. A linear shrinkage of 26–27% was determined. The remaining porosity fraction was 9.0%. No free graphite formation, and almost no η-phase formation occurred. WC grain growth was observed. 76% of the WC grains measured were in the suitable size range for metal cutting tool applications. A hardness of 1157 HV10 and a Palmqvist fracture toughness of 12 MPam was achieved. The achieved microstructure exhibits a high porosity fraction and local cracks. As a result, vat photopolymerization can become an alternative forming method for cemented carbide components if the amount of residual porosity and defects can be reduced.
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Andreu, Alberto, Pei-Chen Su, Jeong-Hwan Kim, Chin Siang Ng, Sanglae Kim, Insup Kim, Jiho Lee, Jinhong Noh, Alamelu Suriya Subramanian, and Yong-Jin Yoon. "4D printing materials for vat photopolymerization." Additive Manufacturing 44 (August 2021): 102024. http://dx.doi.org/10.1016/j.addma.2021.102024.
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Wilts, Emily M., Allison M. Pekkanen, B. Tyler White, Viswanath Meenakshisundaram, Donald C. Aduba, Christopher B. Williams, and Timothy E. Long. "Vat photopolymerization of charged monomers: 3D printing with supramolecular interactions." Polymer Chemistry 10, no. 12 (2019): 1442–51. http://dx.doi.org/10.1039/c8py01792a.
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Vallabh, Chaitanya Krishna Prasad, Yue Zhang, and Xiayun Zhao. "In-situ ultrasonic monitoring for Vat Photopolymerization." Additive Manufacturing 55 (July 2022): 102801. http://dx.doi.org/10.1016/j.addma.2022.102801.
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Nath, Shukantu Dev, and Sabrina Nilufar. "Performance Evaluation of Sandwich Structures Printed by Vat Photopolymerization." Polymers 14, no. 8 (April 8, 2022): 1513. http://dx.doi.org/10.3390/polym14081513.
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Additive manufacturing such as vat photopolymerization allows to fabricate intricate geometric structures than conventional manufacturing techniques. However, the manufacturing of lightweight sandwich structures with integrated core and facesheet is rarely fabricated using this process. In this study, photoactivatable liquid resin was used to fabricate sandwich structures with various intricate core topologies including the honeycomb, re-entrant honeycomb, diamond, and square by a vat photopolymerization technique. Uniaxial compression tests were performed to investigate the compressive modulus and strength of these lightweight structures. Sandwich cores with the diamond structure exhibited superior compressive and weight-saving properties whereas the re-entrant structures showed high energy absorption capacity. The fractured regions of the cellular cores were visualized by scanning electron microscopy. Elastoplastic finite element analyses showed the stress distribution of the sandwich structures under compressive loading, which are found to be in good agreement with the experimental results. Dynamic mechanical analysis was performed to compare the behavior of these structures under varying temperatures. All the sandwich structures exhibited more stable thermomechanical properties than the solid materials at elevated temperatures. The findings of this study offer insights into the superior structural and thermal properties of sandwich structures printed by a vat photopolymerization technique, which can benefit a wide range of engineering applications.
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Schwarzer-Fischer, Eric, Anne Günther, Sven Roszeitis, and Tassilo Moritz. "Combining Zirconia and Titanium Suboxides by Vat Photopolymerization." Materials 14, no. 9 (May 4, 2021): 2394. http://dx.doi.org/10.3390/ma14092394.
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A recently developed multi-ceramic additive manufacturing process (multi-CAMP) and an appropriate device offer a multi-material approach by vat photopolymerization (VPP) of multi-functionalized ceramic components. However, this process is limited to ceramic powders with a certain translucency for visible light. Electrically conductive ceramic powders are therefore ruled out because of their light-absorbing behavior and dark color. The goal of the collaborative work described in the article was to develop a material combination for this multi-material approach of the additive vat photopolymerization method which allows for combining electrical conductivity and electrical insulation plus high mechanical strength in co-sintered ceramic components. As conductive component titanium suboxides are chosen, whereas zirconia forms the mechanically stable and insulation part. Since titanium suboxides cannot be used for vat photopolymerization due to their light-absorbing behavior, titania is used instead. After additive manufacturing, the two-component parts are co-sintered in a reducing atmosphere to transform the titania into its suboxides and, thus, attaining the desired property combination. The article describes the challenges of the co-processing of both materials due to the complex optical properties of titania. Furthermore, the article shows successfully co-sintered testing parts of the material combination of zirconia/titanium suboxide which are made by assembling single-material VPP components in the green state and subsequent common thermal treatment. The results of microstructural and interface investigations such as electrical measurements are discussed.
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Sun, Ke, Xiaotong Peng, Zengkang Gan, Wei Chen, Xiaolin Li, Tao Gong, and Pu Xiao. "3D Printing/Vat Photopolymerization of Photopolymers Activated by Novel Organic Dyes as Photoinitiators." Catalysts 12, no. 10 (October 19, 2022): 1272. http://dx.doi.org/10.3390/catal12101272.
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Even though numerous organic dyes which are used as photoinitiators/photocatalysts during photopolymerization have been systematically investigated and collected in previous reviews, further designs of these chromophores and the developments in high-performance photoinitiating systems have emerged in recent years, which play the crucial role in 3D printing/Vat polymerization. Here, in this mini-review, various families of organic dyes that are used as newly synthesized photoinitiators/photocatalysts which were reported in literature during 2021–2022 are specified by their photoinitiation mechanisms, which dominate their performance during photopolymerization, especially in 3D printing. Markedly, visible light-induced polymerization could be employed in circumstances not only upon the irradiation of artificial light sources, e.g., in LEDs, but also in sunlight irradiation. Furthermore, a short overview of the achievements of newly developed mechanisms, e.g., RAFT, photoinitiator-RAFT, and aqueous RAFT using organic chromophores as light-harvesting compounds to induce photopolymerization upon visible light irradiation are also thoroughly discussed. Finally, the reports on the semiconducting nanomaterials that have been used as photoinitiators/photocatalysts during photopolymerization are also introduced as perspectives that are able to expand the scope of 3D printing and materials science due to their various advantages such as high extinction coefficients, broad absorption spectra, and having multiple molecular binding points.
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Zhang, Feng, Liya Zhu, Zongan Li, Shiyan Wang, Jianping Shi, Wenlai Tang, Na Li, and Jiquan Yang. "The recent development of vat photopolymerization: A review." Additive Manufacturing 48 (December 2021): 102423. http://dx.doi.org/10.1016/j.addma.2021.102423.
Full textDissertations / Theses on the topic "Vat photopolymerization"
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Nath, Shukantu Dev. "FABRICATION AND PERFORMANCE EVALUATION OF SANDWICH PANELS PRINTED BY VAT PHOTOPOLYMERIZATION." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2883.
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Sandwich panels serve many purposes in engineering applications. Additive manufacturing opened the door for easy fabrication of the sandwich panels with different core structures. In this study, additive manufacturing technique, experiments, and numerical analysis are combined to evaluate the mechanical properties of sandwich panels with different cellular core structures. The sandwich panels having honeycomb, re-entrant honeycomb, diamond, square core topologies are printed with the vat photopolymerization technique. Uniaxial compression testing is performed to determine the compressive modulus, strength, and specific strength of these lightweight panels. Elasto-plastic finite element analysis having good similarities with the experimental results provided a preview of the stress distribution of the sandwich panels under applied loading. The imaging of the tested samples showed the fractured regions of the cellular cores. Dynamic mechanical analysis of the panels provided scope to compare the performance of panels and solid materials with the variation of temperature. Sandwich panels with the diamond structure exhibit better compressive properties and specific strength while the re-entrant structure offers high energy absorption capacity. The sandwich structures provided better thermo-mechanical properties than the solid material. The findings of this study offer insights into the mechanical properties of sandwich panels printed with vat photopolymerization technique which can benefit a wide range of engineering applications.
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Chartrain, Nicholas. "Designing Scaffolds for Directed Cell Response in Tissue Engineering Scaffolds Fabricated by Vat Photopolymerization." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/95939.
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Vat photopolymerization (VP) is an additive manufacturing (AM) technology that permits the fabrication of parts with complex geometries and feature sizes as small as a few microns. These attributes make VP an attractive option for the fabrication of scaffolds for tissue engineering. However, there are few printable materials with low cytotoxicity that encourage cellular adhesion. In addition, these resins are not readily available and must be synthesized. A novel resin based on 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS) and poly(ethylene glycol) diacrylate (PEGDA) was formulated and printed using VP. The mechanical properties, water content, and high fidelity of the scaffold indicated promise for use in tissue engineering applications. Murine fibroblasts were observed to successfully adhere and proliferate on the scaffolds.
The growth, migration, and differentiation of a cell is known to dependent heavily on its microenvironment. In engineered constructs, much of this microenvironment is provided by the tissue scaffold. The physical environment results from the scaffold's geometrical features, including pore shape and size, porosity, and overall dimensions. Each of these parameters are known to affect cell viability and proliferation, but due to the difficulty of isolating each parameter when using scaffold fabrication techniques such as porogen leaching and gas foaming, conflicting results have been reported. Scaffolds with pore sizes ranging from 200 to 600 μm were fabricated and seeded with murine fibroblasts. Other geometric parameters (e.g., pore shape) remained consistent between scaffold designs. Inhomogeneous cell distributions and fewer total cells were observed in scaffolds with smaller pore sizes (200-400 μm). Scaffolds with larger pores had higher cell densities that were homogeneously distributed. These data suggest that tissue scaffolds intended to promote fibroblast proliferation should be designed to have pore at least 500 μm in diameter.
Techniques developed for selective placement of dissimilar materials within a single VP scaffold enabled spatial control over cellular adhesion and proliferation. The multi-material scaffolds were fabricated using an unmodified and commercially available VP system. The material preferences of murine fibroblasts which resulted in their inhomogeneous distribution within multi-material scaffolds were confirmed with multiple resins and geometries. These results suggest that multi-material tissue scaffolds fabricated with VP could enable multiscale organization of cells and material into engineered constructs that would mimic the function of native tissue.Doctor of Philosophy
Vat photopolymerization (VP) is a 3D printing (or additive manufacturing) technology that is capable of fabricating parts with complex geometries with very high resolution. These features make VP an attractive option for the fabrication of scaffolds that have applications in tissue engineering. However, there are few printable materials that are biocompatible and allow cells attachment. In addition, those that have been reported cannot be obtained commercially and their synthesis requires substantial resources and expertise. A novel resin composition formulated from commercially available components was developed, characterized, and printed. Scaffolds were printed with high fidelity. The scaffolds had mechanical properties and water contents that suggested they might be suitable for use in tissue engineering. Fibroblast cells were seeded on the scaffolds and successfully adhered and proliferated on the scaffolds. The growth, migration, and differentiation of cells is influenced by the environmental stimuli they experience. In engineered constructs, the scaffold provides many of stimuli. The geometrical features of scaffolds, including how porous they are, the size and shape of their pores, and their overall size are known to affect cell growth. However, scaffolds that have a variety of pore sizes but identical pore shapes, porosities, and other geometric parameters cannot be fabricated with techniques such as porogen leaching and gas foaming. This has resulted in conflicting reports of optimal pore sizes. In this work, several scaffolds with identical pore shapes and porosities but pore sizes ranging from 200 μm to 600 μm were designed and printed using VP. After seeding with cells, scaffolds with large pores (500-600 μm) had a large number of evenly distributed cells while smaller pores resulted in fewer cells that were unevenly distributed. These results suggest that larger pore sizes are most beneficial for culturing fibroblasts. Multi-material tissue scaffolds were fabricated with VP by selectively photocuring two materials into a single part. The scaffolds, which were printed on an unmodified and commercially available VP system, were seeded with cells. The cells were observed to have attached and grown in much larger numbers in certain regions of the scaffolds which corresponded to regions built from a particular resin. By selectively patterning more than one material in the scaffold, cells could be directed towards certain regions and away from others. The ability to control the location of cells suggests that these printing techniques could be used to organize cells and materials in complex ways reminiscent of native tissue. The organization of these cells might then allow the engineered construct to mimic the function of a native tissue.
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Sirrine, Justin Michael. "Tailoring Siloxane Functionality for Lithography-based 3D Printing." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/97196.
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Polymer synthesis and functionalization enabled the tailoring of polymer functionality for additive manufacturing (AM), elastomer, and biological applications. Inspiration from academic and patent literature prompted an emphasis on polymer functionality and its implications on diverse applications. Critical analysis of existing elastomers for AM aided the synthesis and characterization of novel photopolymer systems for lithography-based 3D printing. Emphasis on structure-processing-property relationships facilitated the attainment of success in proposed applications and prompted further fundamental understanding for systems that leveraged poly(dimethyl siloxane)s (PDMS), aliphatic polyesters, polyamides, and polyethers for emerging applications.
The thiol-ene reaction possesses many desirable traits for vat photopolymerization (VP) AM, namely that it proceeds rapidly to high yield, does not undergo significant side reactions, remains tolerant of the presence of water or oxygen, and remains regiospecific. Leveraging these traits, a novel PDMS-based photopolymer system was synthesized and designed that underwent simultaneous chain extension and crosslinking, affording relatively low viscosity prior to photocuring but the modulus and tensile strain at break properties of higher molecular weight precursors upon photocuring. A monomeric competition study confirmed chemical preference for the chain-extension reaction in the absence of diffusion. Photocalorimetry, photorheology, and soxhlet extraction measured photocuring kinetics and demonstrated high gel fractions upon photocuring. A further improvement on the low-temperature elastomeric behavior occurred via introduction of a small amount of diphenylsiloxane or diethylsiloxane repeating units, which successfully suppressed crystallization and extended the rubbery plateau close to the glass transition temperature (Tg) for these elastomers. Finally, a melt polymerization of PDMS diamines in the presence of a disiloxane diamine chain extender and urea afforded isocyanate-free polyureas in the absence of solvent and catalyst. Dynamic mechanical analysis (DMA) measured multiple, distinct α-relaxations that suggested microphase separation. This work leverages the unique properties of PDMS and provides multiple chemistries that achieve elastomeric properties for a variety of applications.
Similar work of new polymers for VP AM was performed that leveraged the low Tg poly(propylene glycol) (PPG) and poly(tri(ethylene glycol) adipate) (PTEGA) for use in tissue scaffolding, footwear, and improved glove grip performance applications. The double endcapping of a PPG diamine with a diisocyanate and then hydroxyethyl acrylate provided a urethane/urea-containing, photocurable oligomer. Supercritical fluid chromatography with evaporative light scattering detection elucidated oligomer molecular weight distributions with repeat unit resolution, while the combination of these PPG-containing oligomers with various reactive diluents prior to photocuring yielded highly tunable and efficiently crosslinked networks with wide-ranging thermomechanical properties. Functionalization of the PTEGA diol with isocyanatoethyl methacrylate yielded a photocurable polyester for tissue scaffolding applications without the production of acidic byproducts that might induce polymer backbone scission. Initial VP AM, cell viability experiments, and modulus measurements indicate promise for use of these PTEGA oligomers for the 3D production of vascularized tissue scaffolds.
Similar review of powder bed fusion (PBF) patent literature revealed a polyamide 12 (PA12) composition that remained melt stable during PBF processing, unlike alternative commercial products. Further investigation revealed a fundamental difference in polymer backbone and endgroup chemical structure between these products, yielding profound differences for powder recyclability after printing. An anionic dispersion polymerization of laurolactam in the presence of a steric stabilizer and initiator yielded PA12 microparticles with high sphericity directly from the polymerization without significant post-processing requirements. Steric stabilizer concentration and stirring rate remained the most important variables for the control of PA12 powder particle size and melt viscosity. Finally, preliminary fusion of single-layered PA12 structures demonstrated promise and provided insight into powder particle size and melt viscosity requirements.PHD
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Scott, Philip Jonathan. "Advancing Elastomers to Additive Manufacturing Through Tailored Photochemistry and Latex Design." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99311.
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Additive manufacturing (AM) fabricates complex geometries inaccessible through other
manufacturing techniques. However, each AM platform imposes unique process-induced
constraints which are not addressed by traditional polymeric materials. Vat photopolymerization
(VP) represents a leading AM platform which yields high geometric resolution, surface finish, and
isotropic mechanical properties. However, this process requires low viscosity (<20 Pa·s)
photocurable liquids, which generally restricts the molecular weight of suitable VP precursors.
This obstacle, in concert with the inability to polymerize high molecular weight polymers in the
printer vat, effectively limits the molecular weight of linear network strands between crosslink
points (Mc) and diminishes the mechanical and elastic performance of VP printed objects.
Polymer colloids (latex) effectively decouple the relationship between viscosity and
molecular weight by sequestering large polymer chains within discrete, non-continuous particles
dispersed in water, thereby mitigating long-range entanglements throughout the colloid.
Incorporation of photocrosslinking chemistry into the continuous, aqueous phase of latex
combined photocurability with the rheological advantages of latex and yielded a high molecular
weight precursor suitable for VP. Continuous-phase photocrosslinking generated a hydrogel
scaffold network which surrounded the particles and yielded a solid "green body" structure.
Photorheology elucidated rapid photocuring behavior and tunable green body storage moduli
based on scaffold composition. Subsequent water removal and annealing promoted particle
coalescence by penetration through the scaffold, demonstrating a novel approach to semiinterpenetrating
network (sIPN) formation. The sIPN's retained the geometric shape of the
photocured green body yet exhibited mechanical properties dominated by the high molecular
weight latex polymer. Dynamic mechanical analysis (DMA) revealed shifting of the latex polymer
and photocrosslinked scaffold Tg's to a common value, a well-established phenomenon due phasemixing
in (s)IPN's. Tensile analysis confirmed elastic behavior and ultimate strains above 500%
for printed styrene-butadiene rubber (SBR) latexes which confirmed the efficacy of this approach
to print high performance elastomers.
Further investigations probed the versatility of this approach to other polymer compositions
and a broader range of latex thermal properties. Semibatch emulsion polymerization generated a
systematic series of random copolymer latexes with varied compositional ratios of hexyl
methacrylate (HMA) and methyl methacrylate (MMA), and thus established a platform for
investigating the effect of latex particle thermal properties on this newly discovered latex
photoprocessing approach. Incorporation of scaffold monomer, N-vinyl pyrrolidone (NVP), and
crosslinker, N,N'-methylene bisacrylamide (MBAm), into the continuous, aqueous phase of each
latex afforded tunable photocurability. Photorheology revealed higher storage moduli for green
bodies embedded with glassy latex particles, suggesting a reinforcing effect. Post-cure processing
elucidated the necessity to anneal the green bodies above the Tg of the polymer particles to promote
flow and particle coalescence, which was evidenced by an optical transition from opaque to
transparent upon loss of the light-scattering particle domains. Differential scanning calorimetry
(DSC) provided a comparison of the thermal properties of each neat latex polymer with the
corresponding sIPN.
Another direction investigated the modularity of this approach to 3D print mixtures of
dissimilar particles (hybrid colloids). Polymer-inorganic hybrid colloids containing SBR and
silica nanoparticles provided a highly tunable route to printing elastomeric nanocomposite sIPN's.
The bimodal particle size distribution introduced by the mixture of SBR (150 nm) and silica (12
nm) nanoparticles enabled tuning of colloid behavior to introduce yield-stress behavior at high
particle concentrations. High-silica hybrid colloids therefore exhibited both a shear-induced
reversible liquid-solid transition (indicated by a modulus crossover) and irreversible
photocrosslinking, which established a unique processing window for UV-assisted direct ink write
(UV-DIW) AM. Concentric cylinder rheology probed the yield-stress behavior of hybrid colloids
at high particle concentrations which facilitated both the extrusion of these materials through the
UV-DIW nozzle and the retention of their as-deposited shaped during printing. Photorheology
confirmed rapid photocuring of all hybrid colloids to yield increased moduli capable of supporting
subsequent layers. Scanning electron microscopy (SEM) confirmed well-dispersed silica
aggregates in the nanocomposite sIPN's. DMA and tensile confirmed significant reinforcement
of (thermo)mechanical properties as a result of silica incorporation. sIPN's with relative weight
ratio of 30:70 silica:SBR achieved maximum strains above 300% and maximum strengths over 10
MPa.
In a different approach to enhancing VP part mechanical properties, thiol-ene chemistry
provided simultaneous linear chain extension and crosslinking in oligomeric diacrylate systems,
providing tunable increases to Mc of the photocured networks. Hydrogenated polybutadiene
diacrylate (HPBDA) oligomers provided the first example of hydrocarbon elastomer
photopolymers for VP. 1,6-hexanedithiol provided a miscible dithiol chain extender which
introduced linear thiol-ene chain extension to compete with acrylate crosslinking. DMA and
tensile confirmed a decrease in Tg and increased strain-at-break with decreased crosslink density.
Other work investigated the synthesis and characterization of first-ever phosphonium
polyzwitterions. Free radical polymerization synthesized air-stable triarylphosphine-containing
polymers and random copolymers from the monomer 4-(diphenylphosphino) styrene (DPPS). 31P
NMR spectroscopy confirmed quantitative post-polymerization alkylation of pendant
triarylphosphines to yield phosphonium ionomers and polyzwitterions. Systematic comparison of
neutral, ionomer, and polyzwitterions elucidated significant (thermo)mechanical reinforcement by
interactions between large phosphonium sulfobetaine dipoles. Broadband dielectric spectroscopy
(BDS) confirmed the presence of these dipoles through significant increases in static dielectric
content. Small-angle X-ray scattering (SAX) illustrated ionic domain formation for all charged
polymers.Doctor of Philosophy
Additive manufacturing (AM) revolutionizes the fabrication of complex geometries, however the utility of these 3D objects for real world applications remains hindered by characteristically poor mechanical properties. As a primary example, many AM process restrict the maximum viscosity of suitable materials which limits their molecular weight and mechanical properties. This dissertation encompasses the design of new photopolymers to circumvent this restriction and enhance the mechanical performance of printed materials, with an emphasis on elastomers. Primarily, my work investigated the use of latex polymer colloids, polymer particles dispersed in water, as a novel route to provide high molecular weight polymers necessary for elastic properties in a low viscosity, liquid form. The addition of photoreactive molecules into the aqueous phase of latex introduces the necessary photocurability for vat photopolymerization (VP) AM. Photocuring in the printer fabricates a three-dimensional object which comprises a hydrogel embedded with polymer particles. Upon drying, these particles coalesce by penetrating through the hydrogel scaffold without disrupting the printed shape and provide mechanical properties comparable with the high molecular weight latex polymer. As a result, this work introduces high molecular weight, high performance polymers to VP and reimagines latex applications beyond 2D coatings. Further investigations demonstrate the versatility of this approach beyond elastomers with successful implementations with glassy polymers and inorganic (silica) particles which yield nanocomposites.
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Cashman, Mark Francis. "Siloxane-Based Reinforcement of Polysiloxanes: from Supramolecular Interactions to Nanoparticles." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/100134.
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Polysiloxanes represent a unique class of synthetic polymers, employing a completely inorganic backbone structure comprised of repeating –(Si–O)n– 'siloxane' main chain linkages. This results in an assortment of diverse properties exclusive to the siloxane bond that clearly distinguish them from the –(C–C)n– backbone of purely organic polymers.
Previous work has elucidated a methodology for fabricating flexible and elastic crosslinked poly(dimethyl siloxane) (PDMS) constructs with high Mc through a simultaneous crosslinking and chain-extension methodology. However, these constructs suffer the poor mechanical properties typical of lower molecular weight crosslinked siloxanes (e.g. modulus, tear strength, and strain at break). Filled PDMS networks represent another important class of elastomers in which fillers, namely silica and siloxane-based fillers, impart improved mechanical properties to otherwise weak PDMS networks. This work demonstrates that proper silicon-based reinforcing agent selection (e.g. siloxane-based MQ copolymer nanoparticles) and incorporation provides a synergistic enhancement to mechanical properties, whilst maintaining a low viscosity liquid composition, at high loading content, without the use of co-solvents or heating. Rheological analysis evaluates the viscosity while photorheology and photocalorimetry measurements evaluate rate and extent of curing of the various MQ-loaded formulations, demonstrating theoretical printability up to 40 wt% MQ copolymer nanoparticle incorporation. Dynamic mechanical analysis (DMA) and tensile testing evaluated thermomechanical and mechanical properties of the cured nanocomposites as a function of MQ loading content, demonstrating a 3-fold increase in ultimate stress at 50 wt% MQ copolymer nanoparticle incorporation. VP AM of the 40 wt% MQ-loaded, photo-active PDMS formulation demonstrates facile amenability of photo-active PDMS formulations with high MQ-loading content to 3D printing processes with promising results.
PDMS polyureas represent an important class of elastomers with unique properties derived from the synergy between the nonpolar nature, unusual flexibility, and low glass transition temperature (Tg) afforded by the backbone siloxane linkages (-Si-O)n- of PDMS and the exceptional hydrogen bond ordering and strength evoked by the bidentate hydrogen bonding of urea. The work herein presents an improved melt polycondensation synthetic methodology, which strategically harnesses the spontaneous pyrolytic degradation of urea to afford a series of PDMS polyureas via reactions at high temperatures in the presence of telechelic amine-terminated oligomeric poly(dimethyl siloxane) (PDMS1.6k-NH2) and optional 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BATS) chain extender. This melt polycondensation approach uniquely circumvents the accustomed prerequisite of isocyanate monomer, solvent, and metal catalysts to afford isocyanate-free PDMS polyureas using bio-derived urea with the only reaction byproduct being ammonia, a fundamental raw ingredient for agricultural and industrial products.
As professed above, reinforcement of polysiloxane materials is ascertained via the incorporation of reinforcing fillers or nanoparticles (typically fumed silica) or blocky or segmented development of polymer chains eliciting microphase separation, in order to cajole the elongation potential of polysiloxanes. Herein, a facile approach is detailed towards the synergistic fortification of PDMS-based materials through a collaborative effort between both primary methods of polysiloxane reinforcement. A novel one-pot methodology towards the facile, in situ incorporation of siloxane-based MQ copolymer nanoparticles into segmented PDMS polyureas to afford MQ-loaded thermoplastic and thermoplastic elastomer PDMS polyureas is detailed. The isocyanate-free melt polycondensation achieves visible melt dispersibility of MQ copolymer nanoparticles (good optical clarity) and affords segmented PDMS polyureas while in the presence of MQ nanoparticles, up to 40 wt% MQ, avoiding post-polymerization solvent based mixing, the only other reported alternative. Incorporation of MQ copolymer nanoparticles into segmented PDMS polyureas provides significant enhancements to modulus and ultimate stress properties: results resemble traditional filler effects and are contrary to previous studies and works discussed in Chapter 2 implementing MQ copolymer nanoparticles into chemically-crosslinked PDMS networks. In situ MQ-loaded, isocyanate-free, segmented PDMS polyureas remain compression moldable, affording transparent, free-standing films.Master of Science
Polysiloxanes, also referred to as 'silicones' encompass a unique and important class of polymers harboring an inorganic backbone. Polysiloxanes, especially poly(dimethyl siloxane) (PDMS) the flagship polymer of the family, observe widespread utilization throughout industry and academia thanks to a plethora of desirable properties such as their incredible elongation potential, stability to irradiation, and facile chemical tunability. A major complication with the utilization of polysiloxanes for mechanical purposes is their poor resistance to defect propagation and material failure. As a result polysiloxane materials ubiquitously observe reinforcement in some fashion: reinforcement is achieved either through the physical or chemical incorporation of a reinforcing agent, such as fumed silica, or through the implementation of a chemical functionality that facilitates reinforcement via phase separation and strong associative properties, such as hydrogen bonding. This research tackles polysiloxane reinforcement via both of these strategies. Facile chemical modification permits the construction PDMS polymer chains that incorporate hydrogen bonding motifs, which phase separate to afford hydrogen bond-reinforced phases that instill vast improvements to elastic behavior, mechanical and elongation properties, and upper-use temperature. Novel nanocomposite formulation through the incorporation of MQ nanoparticles (which observe widespread usage in cosmetics) facilitate further routes toward improved mechanical and elongation properties. Furthermore, with growing interest in additive manufacturing strategies, which permit the construction of complex geometries via an additive approach (as opposed to conventional manufacturing processes, which require subtractive approaches and are limited in geometric complexity), great interest lies in the capability to additively manufacture polysiloxane-based materials. This work also illustrates the development of an MQ-reinforced polysiloxane system that is amenable to conventional vat photopolymerization additive manufacturing: chemical modification of PDMS polymer chains permits the installation of UV-activatable crosslinking motifs, allowing solid geometries to be constructed from a liquid precursor formulation.
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Liu, De-Feng, and 劉德風. "Research and Development of Mobile Device Vat Photopolymerization 3D Printing System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5g2c5w.
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碩士國立臺灣科技大學
機械工程系
105
This study is about a mobile device vat photopolymerization 3D printing system. The system uses a mobile device instead of an expensive laser or a UV lamp to be the light source and pattern generator. Using a timing belt and a linear slide instead of a screw and a shaft to drive the Z-axis stage. This system allows larger positioning tolerance and has high z-axis resolution at the same time by virtue of the flexibility of timing belt. Besides, this study established a standard operating procedure for adjusting the important parameter in the 3D printing process, the “exposure time”. This procedure can quantify the curing degree of the resin by using the Fourier Transform Infrared Spectrometer (FTIR). The quantified curing degree can be used to readjust the exposure time of the 3D printing system when the light source is changed (e.g., the light source is changed from a smartphone to a tablet or another smartphone), let the 3D printing system can operate like the light source is never changed. Finally, measuring the dimensional deviation of the mobile device 3D printing system by printing some samples. The result shows that the dimensional deviation of the X-Y axis is under 260μm by using commercial resin “NT-01” and is under 180μm by adding inhibitor into the resin “NT-01”. The Z-axis dimensional deviation is under 60μm no matter adding inhibitor or not.
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Ruan, Jyun-Min, and 阮俊民. "The Study on CoCrMo Alloy Additive Manufacturing Technology of Vat Photopolymerization." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/26k45p.
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碩士國立臺北科技大學
機電整合研究所
105
The purpose of this study is to use CoCrMo alloy to produce metal elements with high strength and accuracy characteristics by additive manufacturing technology of Stereolithography. The method is based on using CoCrMo alloy powder with addition photopolymierizable syntheric resin composite slurry. In order to reduce shrinkage and defects, investigated the slurry formulation control of tape casting process to achieve high solid content and precise size. Hence, the sintered part’s direction of shrinkage, density, and the mechanical properties of bending strength, hardness and impact energy were analysed. The result showed that the solid content of 85 wt% CoCrMo alloy dispersed slurry sintered at 1320 ℃ and held 1 hr, the linear shrinkage rate of the measurement results that triaxial average shrinkage was 25.4~25.7 % which X and Y axial shrinkage error range was about 4 % and Z was about 3 %. The average density was 98.6 %.The Victor hardness measurement was 436.3 Hv. The impact average energy was 1.45 J. The average bending strength was 1092.3 MPa.
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Chang, Chih-Hsiang, and 張智翔. "The Development of the Bottom-Up Vat Photopolymerization System for Ceramic Material." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8yzjtt.
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碩士國立臺北科技大學
機電整合研究所
105
This study, dissertates the Vat Photopolymerization Process for Ceramic (VPPC) system with solvent-free slurry, utilized to large-size ceramic workpieces with a hollow structure. It utilizes a light source to cure the slurry to form three dimensional parts. By using Bottom-Up approach and solvent-free slurry, there occurs very less wastage and the slurry is reusable. The VPPC system is configured with two Full HD projectors to generate a build volume of 128mm*114mm*150mm in length, width and height. It also consists of a scraper installed on X-axis platform to clean the uncured slurry from the bottom of the tank. The viscosity of the solvent-free slurry is adjusted to 1000cP (5rpm) to attain a good fluidity. By optimizing different parameters, the shortest time achieved to form each layer is 15 seconds. This research also discusses in depth about the process, system design, control system, PC interface setting, image deformation correction and followed by benchmark tests. The VPPC system has shown the capability in fabricating the hollow structures. This study can also adapt different ceramic materials and produce tailored mechanical properties of the resultant parts. This process also can be utilized to fabricate the biomimicking bone implants or similar lattice structures. By using biocompatible ceramic materials, the implant structures not be used for prototyping but also be used for implant surgeries.
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Chen, Zheng-Yu, and 陳政宇. "Adaptive Additive Manufacturing Technology for Desk-top LCD-Based Vat-photopolymerization System." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/26eezs.
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碩士國立臺灣科技大學
自動化及控制研究所
107
Most of today's additive manufacturing systems, the thickness between layers is fixed. It will result in lengthy fabrication time for a thinner layer thickness. If a faster speed is desired, the layer number is reduced which means the layer thickness must be increased. So the main purpose of this study is to reduce the object fabrication time of high-resolution Desk-top LCD-Based vat-photopolymerization System via adaptive additive manufacturing method within acceptable tolerances. It was found that the most time-consuming part of a Desk-top LCD-Based vat-photopolymerization System process is the process rising and falling of Z-axis motion. Therefore, the aim of this study is to reduce the number of layers by adaptive slicing algorithm, thereby speeding up the overall fabrication time. Researcher will pre-process the mask data, and combine with the STL triangle grid data, and calculate the center gap on distance between two neighbor layer through the adaptive slicing algorithm. Finally, the G-code that can be used by a Desk-top LCD-Based vat-photopolymerization System is generated by the post-processing method. The user can set the maximum length δ_m according to the desired requirements, and make a balance between the accuracy and the printing time. This study investigated four different symmetrical objects, by using computer simulation and actual production of adaptive slicing thickness. From the experimental results, three different asymmetrical objects with the proposed method with condition of δ_m=50μm, the fabrication time can be saved up to 15.87% compared to the fixed layer slicing. The system forming efficiency can be effectively improved.
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Wu, Kun-Ta, and 巫昆達. "Research on High-speed UV LCD Vat Photopolymerization 3D Printing System Development." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/jjp39t.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
107
Based on the 3D printing system developed by the laboratory, this thesis develops the LCD-type photo-curing system with UV light source for the first time, and analyzes the influence of the light source factor on the printing. Since it is the first time to use this UV LED light source film group, in order to measure the power supply of the film group, the power supply is used to supply the voltage and current required by the light source film group and the POWERMETER instrument is used to measure the supply wattage. The intensity of light energy. In addition, the pattern exposure experiment was used to test the uniformity of light, formability and precision. Design a heat dissipation system to reduce the temperature of the high-energy light source module to increase the service life of the module and prevent excessive heat energy from affecting the speed at which the resin is cured. In the machine control and LCD panel graphic display, the Raspberry Pi with Python program for transmission control, in order to do the overall print test. At the end of the experiment, the 405nm wavelength UV LED light source module was compared with the commercial machines Phrozen and Arkuretta used by most consumers. Although the three are the LCD type machine, they use different light source modules. The difference in exposure light source can affect the results of printing, such as dimensional accuracy, sharpness of the edge of the object, and so on.
Books on the topic "Vat photopolymerization"
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Wang, Xiaolong. Vat Photopolymerization 3D Printing: Processes, Materials, and Applications. Elsevier, 2024.
Find full textBook chapters on the topic "Vat photopolymerization"
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Gibson, Ian, David Rosen, Brent Stucker, and Mahyar Khorasani. "Vat Photopolymerization." In Additive Manufacturing Technologies, 77–124. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-56127-7_4.
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Bongiovanni, Roberta, and Alessandra Vitale. "Vat Photopolymerization." In High Resolution Manufacturing from 2D to 3D/4D Printing, 17–46. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-13779-2_2.
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Gibson, Ian, David Rosen, and Brent Stucker. "Vat Photopolymerization Processes." In Additive Manufacturing Technologies, 63–106. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2113-3_4.
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Srivastava, Manu, Sandeep Rathee, Sachin Maheshwari, and T. K. Kundra. "Additive Manufacturing Processes Utilizing Vat Photopolymerization." In Additive Manufacturing, 63–80. Boca Raton, FL : CRC Press/Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9781351049382-6.
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Aguirresarobe, Robert Hernández, Fermín Elizalde Iraizoz, Haritz Sardon, and Antxón Santamaría. "Photo Rheometry of Waterborne Polyurethanes for Its Implementation in Vat Photopolymerization." In Springer Proceedings in Materials, 127–31. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27701-7_27.
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Mischkot, Michael, Thomas Hofstätter, Ifigeneia Michailidou, Carlos Herrán Chavarri, Andreas Lunzer, Guido Tosello, David Bue Pedersen, and Hans Nørgaard Hansen. "Performance Simulation and Verification of Vat Photopolymerization Based, Additively Manufactured Injection Molding Inserts with Micro-Features." In Industrializing Additive Manufacturing - Proceedings of Additive Manufacturing in Products and Applications - AMPA2017, 162–68. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66866-6_16.
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Vladić, Gojko, Bojan Banjanin, Nemanja Kašiković, and Živko Pavlović. "Vat photopolymerization." In Polymers for 3D Printing, 65–74. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-818311-3.00018-5.
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Li, Xiangjia, and Yong Chen. "Vat-Photopolymerization-Based Ceramic Manufacturing." In Additive Manufacturing Processes, 81–96. ASM International, 2020. http://dx.doi.org/10.31399/asm.hb.v24.a0006578.
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Kanematsu, Hideyuki, Dana M. Barry, Rafiqul Noorani, and Paul McGrath. "Medical Applications of Vat Polymerization." In Additive Manufacturing in Biomedical Applications, 1–9. ASM International, 2022. http://dx.doi.org/10.31399/asm.hb.v23a.a0006863.
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Abstract Of the seven additive manufacturing (AM) processes, this article focuses on the vat photopolymerization, or simply vat polymerization, process, while briefly discussing the other six AM processes. Vat polymerization and its characteristics, AM applications in medical fields, and the regulatory challenges of vat polymerization-based bioprinting are presented.
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Davoudinejad, Ali. "Vat photopolymerization methods in additive manufacturing." In Additive Manufacturing, 159–81. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-818411-0.00007-0.
Full textConference papers on the topic "Vat photopolymerization"
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Diptanshu, Erik Young, Chao Ma, Suleiman Obeidat, Bo Pang, and Nick Kang. "Ceramic Additive Manufacturing Using VAT Photopolymerization." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6389.
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The popularity of additive manufacturing for producing porous bio-ceramics using vat photopolymerization in the recent years has gained a lot of impetus due to its high resolution and low surface roughness. In this study, a commercial vat polymerization printer (Nobel Superfine, XYZprinting) was used to create green bodies using a ceramic suspension consisting of 10 vol.% of alumina particles in a photopolymerizable resin. Four different sizes of cubical green bodies were printed out. They were subjected to thermal processing which included de-binding to get rid of the polymer and thereafter sintering for joining of the ceramic particles. The porosity percentage of the four different sizes were measured and compared. The lowest porosity was observed in the smallest cubes (5 mm). It was found to be 43.3%. There was an increase in the porosity of the sintered parts for the larger cubes (10, 15 and 20 mm). However, the difference in the porosity among these sizes was not significant and ranged from 61.5% to 65.2%. The compressive testing of the samples showed that the strength of the 5-mm cube was the maximum among all samples and the compressive strength decreased as the size of the samples increased. These ceramic materials of various densities are of great interest for biomedical applications.
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Shan, Yujie, Aravind Krishnakumar, Zehan Qin, and Huachao Mao. "Smart Resin Vat: Real-Time Detecting Failures, Defects, and Curing Area in Vat Photopolymerization 3D Printing." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85691.
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Abstract Real-time and in-situ printing performance diagnostic in vat photopolymerization is critical to control printing quality, improve process reliability, and reduce wasted time and materials. This paper proposed a low-cost smart resin vat to monitor the printing process and detect the printing faults. Built on a conventional vat photopolymerization process, we added equally spaced thermistors along the edges of the resin vat. During printing, polymerization heat transferred to the edges of the resin vat, which increased thermistors’ temperature and enhanced resistances. The heat flux received at each thermistor varied with the distance to the place of photopolymerization. The temperature profiles of all thermistors were determined by the curing image pattern in each layer, and vice versa. Machine learning algorithms were leveraged to infer the printing status from the measured temperatures of these thermistors. Specifically, we proposed a simple and robust Failure Index to detect if the printing was active or terminated. Gaussian process regression was utilized to predict the printing area using the temperature recordings within a layer. The model was trained, validated, and tested using the data set collected by printing six parts. Different printing abnormalities, including printing failures, manual printing pause, and missing features (incorrect printing area), were successfully detected. The proposed approach modified the resin vat only and could be easily applied to all vat photopolymerization processes, including SLA, DLP, and LCD based 3D printing. The limitation and future work are also highlighted.
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Yang, Feimo, Aamer Kazi, Caleb Liu, and Bruce L. Tai. "Separation Process Comparison of Hydrogel Film and PTFE Film in Vat Photopolymerization." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85380.
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Abstract In constrained surface vat photopolymerization, the separation process between a newly printed layer and the vat film has long been a limiting factor for printing speed and feature size. This paper aims to compare the performance of a hydrogel film and a conventionally used polytetrafluoroethylene (PTFE) in terms of separation forces, vertical separation distances, and dimensional accuracies of the printed parts. PTFE is commonly adopted because of its low surface energy and thus low separation force, while the hydrogel film is hypothetically effective because of its repelling nature to the non-polar characteristic in most photopolymers. A custom-designed building platform with an integrated sensor is used to continuously sample the force at 1,000Hz with 0.1N resolution. The separation distance is calculated based on the ascending and descending force profiles. The results show a 26% reduction in separation forces and a 60% reduction in vertical separation distances, with 95% statistical significance when comparing the hydrogel film to the PTFE film. The dimensional accuracies of produced parts in both films are similar.
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Smith, Patrick T., Benjaporn Narupai, S. Cem Millik, Ryan T. Shafranek, and Alshakim Nelson. "Development of bovine serum albumin-based resins for additive manufacturing via vat photopolymerization." In Novel Patterning Technologies for Semiconductors, MEMS/NEMS and MOEMS 2020, edited by Eric M. Panning and Martha I. Sanchez. SPIE, 2020. http://dx.doi.org/10.1117/12.2551988.
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Raines, Regan, James B. Day, and Roozbeh (Ross) Salary. "Experimental Characterization of the Mechanical Properties of Medical-Grade Dental Implants, Fabricated Using Vat-Photopolymerization Additive Manufacturing Process." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85436.
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Abstract The overarching goal of this research work is to fabricate mechanically-robust and dimensionally-accurate dental implants for the treatment of dental fractures, anomalies, and structural deformities with a focus on oral and maxillofacial surgery applications. In pursuit of this goal, the objective of the work is to investigate the mechanical properties of several triply periodic minimal surface (TPMS) scaffolds, composed of a medical-grade photopolymer resin, fabricated using digital light processing (DLP) process. DLP is a vat-photopolymerization additive manufacturing process; it has emerged as a high-resolution method for the fabrication of a broad spectrum of biological tissues and constructs for tissue engineering applications. However, the DLP process is intrinsically complex; the complexity of the process stems from complex physiochemical phenomena (such as UV light photopolymerization) as well as resin (photopolymer)-process interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated dental scaffolds. Consequently, physics-based process and material characterization would be an inevitable need. In this study, several TPMS scaffolds (having complex internal geometries) were fabricated, based on a medical-grade photopolymer resin. The compression properties of the fabricated dental scaffolds were measured using a compression testing machine. In addition, the bioactivity of the scaffolds was assessed in a simulated body fluid (SBF). The outcomes of this study pave the way for the fabrication of complex dental implants with tunable medical and functional properties.
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Saracaydin, Renc, and Seth A. Hara. "Additive Manufacturing of Medical Microdevices." In 2022 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/dmd2022-1042.
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Abstract Additive manufacturing is a growing field, but its application in the fabrication of medical microdevices has not been fully explored. Traditionally, medical microdevices are manufactured via a combination of techniques such as photolithography, laser-cutting, and micromolding, which collectively have challenges such as multiple fabrication steps, limited design freedom, high fabrication cost, and significant fabrication time. Micro vat photopolymerization is presented here as an alternative method to produce four different microscale medical devices that have applications in microfluidics, drug delivery, and bioscaffolding. In terms of minimum feature size and resolution, the presented structures are comparable, if not superior, to literature quoted parts fabricated through conventional manufacturing methods. The fabrication steps, process parameters, design considerations, learnings, and future research directions are outlined.
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Shan, Yujie, Praveen Sahu, Raji Sundararajan, and Huachao Mao. "Rapid and Low-Cost Fabrication of Microfluidic Devices Using Liquid Crystal Display-Based 3D Printing." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-96036.
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Abstract Microfluidic devices have been widely investigated for various applications, specifically in the biomedical field, which involve manipulating cells at a sub-micron scale. However, the conventional lithography process with polydimethylsiloxane (PDMS) micro-molding process (soft lithography) involves numerous steps demanding high-end equipment and a cleanroom fueling up the cost and making it a time-consuming process. This paper presents a low-cost yet versatile way to fabricate long microfluidic channels using liquid crystal display (LCD)-based vat photopolymerization 3D printing. The accuracy, resolution and repeatability of the printing process were characterized using various parameter settings. We validated the developed process by 3D-printing four different microfluidic devices with 100 μm wide channels. Subsequently, we successfully demonstrated the formation of a single streamline of breast cancer cells in a microchannel with long and smooth edges. The scanning electron microscopy (SEM) characterization shows a high-quality fabricated channel. This proposed approach aligns with the ongoing efforts toward a versatile, flexible, and fast option for producing the diagnostic device.
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Raines, Regan, and Roozbeh (Ross) Salary. "Investigation of the Effects of Photopolymer Resin Composition on the Mechanical Properties of Complex Dental Constructs, Fabricated Using Digital Light Processing." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95049.
Full textAbstract:
Abstract The overarching goal of this research work is to fabricate mechanically robust, dimensionally accurate, and porous dental structures, potentially used for the treatment of dental fractures, anomalies, as well as structural deformities with a focus on oral and maxillofacial surgery applications. In pursuit of this goal, the objective of the work is to investigate the mechanical properties of dental constructs, composed of medical-grade photopolymer resins and fabricated using digital light processing (DLP) process. The fabricated dental constructs not only are porous, but also have complex microstructures imparted by triply periodic minimal surface (TPMS) designs. This study tests the following central hypothesis: the mechanical properties of DLP-fabricated dental structures are significantly affected by photopolymer resin composition. In addition, the following research question is answered in this study: which of the chosen medical-grade photopolymer resins has the most significant impact on the mechanical properties of fabricated dental structures. DLP is a vat-photopolymerization additive manufacturing process, which has emerged as a high-resolution, robust method for the fabrication of a broad range of biological tissues and constructs for oral and dental tissue engineering applications. In the DLP process, the printing process takes place on the basis of radiation-curable resins or liquid photopolymers. Upon exposure to UV light, the resin materials become a solid (via chemical transformation) through a process known as photopolymerization. The DLP process consists of several parameters (such as layer thickness, cure depth, and UV lamp intensity) that significantly influence the functional properties of fabricated dental structures. In spite of the advantages and engendered applications, DLP is inherently complex; the complexity of the DLP process, to a great extent, stems from complex physio-chemical phenomena (such as UV light photopolymerization) in addition to resin (photopolymer)-process interactions, which may adversely affect not only the surface morphology, but also the mechanical properties and ultimately the functional characteristics of the fabricated dental scaffolds. As a result, integrated physics-guided process and material characterization would be required for optimal fabrication of porous and complex dental structures. Particularly in this study, the influence of three medical-grade photopolymer resins on the compression properties as well as the dimensional accuracy of TPMS dental constructs is systematically investigated. The compression properties of the DLP-fabricated dental constructs are measured using a compression testing machine. Furthermore, the dimensional accuracy of the dental constructs is measured via physical measurements and with the aid of a laser scanner. Besides, analysis of variance (ANOVA) is utilized to identify statistically significant photopolymer resin(s). The outcomes of this study pave the way for high-resolution fabrication of complex and porous dental structures with tunable medical and functional properties.
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Meem, Asma Ul Hosna, Kyle Rudolph, Allyson Cox, Austin Andwan, Timothy Osborn, and Robert Lowe. "Impact of Process Parameters on the Tensile Properties of DLP Additively Manufactured ELAST-BLK 10 UV-Curable Elastomer." In ASME 2021 16th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/msec2021-64002.
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Abstract Digital light processing (DLP) is an emerging vatphotopolymerization-based 3D-printing technology where full layers of photosensitive resin are irradiated and cured with projected ultraviolet (UV) light to create a three-dimensional part layer-by-layer. Recent breakthroughs in polymer chemistry have led to a growing number of UV-curable elastomeric photoresins developed exclusively for vat photopolymerization additive manufacturing (AM). Coupled with the practical manufacturing advantages of DLP AM (e.g., industry-leading print speeds and sub-micron-level print resolution), these novel elastomeric photoresins are compelling candidates for emerging applications requiring extreme flexibility, stretchability, conformability, and mechanically-tunable stiffness (e.g., soft robotic actuators and stretchable electronics). To advance the role of DLP AM in these novel and promising technological spaces, a fundamental understanding of the impact of DLP manufacturing process parameters on mechanical properties is requisite. This paper highlights our recent efforts to explore the process-property relationship for ELAST-BLK 10, a new commercially-available UV-curable elastomer for DLP AM. A full factorial design of experiments is used to investigate the effect of build orientation and layer thickness on the quasi-static tensile properties (i.e., small-strain elastic modulus, ultimate tensile strength, and elongation at fracture) of ELAST-BLK 10. Statistical results, based on a general linear model via ANOVA methods, indicate that specimens with a flat build orientation exhibit the highest elastic modulus, ultimate tensile strength, and elongation at fracture, likely due to a larger surface area that enhances crosslink density during the curing process. Several popular hyperelastic constitutive models (e.g., Mooney-Rivlin, Yeoh, and Gent) are calibrated to our quasi-static tensile data to facilitate component-level predictive analyses (e.g., finite-element modeling) of soft robotic actuators and other emerging soft-matter applications.
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Alrashdan, Abdulrahman, William Jordan Wright, and Emrah Celik. "Light Assisted Hybrid Direct Write Additive Manufacturing of Thermosets." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24525.
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Abstract In the past recent years, numerous studies have been conducted on additive manufacturing of thermosets and thermoset composites. Thermosets are an important class of polymers used in engineering applications. Monomer units in these material systems irreversibly cross-link when external stimuli or a chemical crosslinking agent is applied in terms of the curing or photopolymerization process. Thermally curing thermosets mark unique mechanical properties including, high temperature resistance, strong chemical bond, and structural integrity and therefore these materials find wide range of applications currently. However, direct write additive manufacturing of these material systems at high resolution and at complex geometries is challenging. This is due to the slow curing rate of thermally curing thermoset polymers which can adversely affect the printing process, and the final shape of the printed object. On the other hand, VAT Polymerization additive manufacturing, which is based on curing the photopolymer resin by Ultraviolet (UV) light, can allow the fabrication of complex geometries and excellent surface finish of the printed parts due to the fast curing rate of photopolymers used in this technique. Mechanical properties of photopolymers, however, are usually weaker and more unstable compared to the thermally curing polymers used in the direct write additive manufacturing method. Therefore, this study focuses on taking the advantages of these two thermoset additive manufacturing methods by utilizing both the thermally cured epoxy and photopolymer resins together. Using the direct writing, the resin mixture is extruded though a nozzle and the final 3D object is created on the print bed. Simultaneously, the deposited ink is exposed to the UV light enhancing the yield strength of the printed material and partially curing it. Therefore, thermally cured epoxy is used to obtain the desirable mechanical properties, while the addition of the photopolymer resin allows the thermoset mixture to partially solidify the printed ink when exposed to the UV light. The results achieved in this study showed that, the hybrid additive manufacturing technology is capable of fabricating complex and tall structure which cannot be printable via additive manufacturing method. In addition, mechanical properties of the hybrid thermoset ink are comparable to the thermally cured thermoset polymer indicating the great potential of the light-assisted, hybrid manufacturing to fabricate mechanically strong parts at high geometrical resolution.