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Modern technologies enable treatment planning and the fabrication of clear aligners for the correction of misaligned teeth
Anita Fekonja, Nejc Rošer, Igor Drstvenšek, 2022, kratki znanstveni prispevek

Ključne besede: clear aligners, tooth alignment, digitization, additive manufacturing
Objavljeno v DKUM: 17.01.2023; Ogledov: 502; Prenosov: 30
.pdf Celotno besedilo (479,15 KB)
Gradivo je zbirka in zajema 1 gradivo!

The consolidation of emulsion templating and thiol-ene click chemistry as a route to degradable polyhipes for biomedical applications : doktorska disertacija
Viola Hobiger, 2022, doktorska disertacija

Opis: Thiol-ene click chemistry has been on the rise for the past two decades. In the past years, it has also found its way into the synthesis of porous polymers from emulsion templating (polyHIPEs) due to its versatility and convenience. It is an especially attractive pathway for scaffolds intended for biomedical purposes since the resulting materials are often biocompatible and degradable due to hydrolyzable ester bonds introduced via the thiol monomers. The overall aim of this dissertation was to bring thiol-ene click chemistry with a focus on photopolymerization to the forefront of polyHIPE research, highlighting the great potential in combining the preparation technique of emulsion templating together with thiol-ene click chemistry. A study to understand the mechanisms of emulsion stability with a focus on already established thiol-ene formulations was conducted. It was possible to study and synthesize materials with a bicontinuous pore morphology within this project. Compared to the typical cellular pore morphology of a polyHIPE, a bicontinuous structure could be especially useful for separation applications. Furthermore, it was possible to induce a phase inversion, leading to small polymer particles. One part of the dissertation focused on synthesizing hydrophilic polyHIPEs from poly(ethylene glycol) monomers and a hydrophilic thiol through an oil-in-water high internal phase emulsion. The resulting materials exhibited high porosity and small average pore diameters of 2.2 µm. Water uptake and degradation studies were performed. The potential of the material for drug release was demonstrated with the chosen model drug salicylic acid. Furthermore, a HIPE formulation based on the acrylate 1,6-hexanediol diacrylate and thiol tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate was developed. For the developed poly(acrylate-co-thiol) polyHIPEs, the effect of oxidation thioethers present in the polymer network on the material properties was explored. This investigation was performed firstly to tune material properties, e.g. increase the glass transition temperature and tensile strength, and secondly, to highlight the oxidation properties of thioether-containing polymer networks. The oxidation responsiveness should be considered when a biomedical application is envisioned since inflammatory processes lead to oxidative stress in an organism. The formulation was also investigated for its additive manufacturing potential. The emulsion composition had to be adjusted to obtain a printable emulsion. Furthermore, it was possible to exclude harmful solvents, making the overall printing process more environmentally friendly and less hazardous for operators. A polyHIPE from the biobased vinyl ester O,O‘-(hexahydrofuro[3,2-b]furan-3,6-diyl) divinyl diadipate (GDVA), which was especially promising as a biocompatible and biodegradable scaffold for tissue engineering, was prepared together with different thiol chain-transfer agents. The synthesis of cellular interconnected polyHIPEs from these starting materials proved challenging. However, the first synthesis of a biobased vinyl ester polyHIPE could be reported. A final project was conducted in collaboration with Lithoz GmbH. In collaboration, it was possible to establish the first 3D printed ceramics from high internal phase emulsion precursors. For this purpose, trimethylolpropantriacrylte and the thiol trimethylolpropane tris(3-mercaptopropionate) were employed as monomers together with alumina particles to form a composite polyHIPE which would then be submitted to sintering, resulting in an intrinsically porous printed ceramic, allowing for high customization and complex porous morphologies.
Ključne besede: polyHIPE, thiol-ene, photopolymerization, additive manufacturing
Objavljeno v DKUM: 07.10.2022; Ogledov: 587; Prenosov: 97
.pdf Celotno besedilo (12,79 MB)

Influence of Heat Treatments on Microstructure of Electron Beam Additive Manufactured Ti-6Al-4V Alloy : magistrsko delo
Damir Skuhala, 2020, magistrsko delo

Opis: Additive manufacturing of metallic parts is increasing in popularity and starting to emerge as a new competitive manufacturing process. Printed structures from Ti-6Al-4V titanium alloy, produced by electron beam additive manufacturing (EBAM), possess columnar prior β grains and layer bands, alongside an ultrafine lamellar microstructure, which is prone to low ductility and thus requiring thermal post-processing. Several heat treatments were performed in α + β and β field, in one or multiple stages. The results showed that bi-lamellar microstructure can be obtained, and that selection of annealing temperature and cooling rate determines the morphology, thickness, and distribution of both primary and secondary α features. Mechanical properties were evaluated on three selected heat treatments. Annealing of the As-built condition was performed at 710°C (HT1) and 870°C (HT2), resulting in lamellar microstructure with basketweave morphology. In two-stage heat treatment (HT3), the temperature in the first stage has exceeded β transus, while in the second, annealing was performed again at 870°C. The microstructure was characterized as a mixture of lamellar and bi-lamellar with large α colonies inside the rearranged prior β grains. Air cooling was performed in all HT from the final annealing stage. Strength and hardness have decreased with increasingly coarser microstructural features, while fracture toughness was improved, except in HT1, where the decrease in the fracture toughness was mainly attributed to reduced intrinsic toughening. As-built and HT1 conditions were effected by microstructural texture, causing inconsistent fracture morphology, reduced crack roughness and scattering in results. The influence of texture was decreased by coarser microstructure in HT2, while crack tortuosity was increased. Very unpredictable fracture behaviour was observed in HT3 due to large α colonies, as their orientation determines the areas of ductile or cleavage crack propagation.
Ključne besede: Titanium alloys, Ti-6Al-4V, additive manufacturing, EBAM, heat treatments, microstructural optimization, mechanical properties, fracture toughness
Objavljeno v DKUM: 11.05.2020; Ogledov: 1573; Prenosov: 269
.pdf Celotno besedilo (25,14 MB)

Development of the Next Generation Open Hardware 3D Printer Troublemaker
Blaž Bratuš, 2015, diplomsko delo

Opis: The development of the next generation of 3D printer Troublemaker is described in this project. Since their first development Troublemakers have been in operation for more than a year and we have decided that some design features should be improved. All the design features and parts of the original Troublemaker had to be evaluated and improved or replaced if necessary. All the 3D modelling was done parametrically in SolidWorks. The Troublemaker 3D printer has open-source hardware design and all the documentation will be freely available to anyone.
Ključne besede: development, 3D printer, Troublemaker, additive manufacturing, 3D printing, open source, open hardware
Objavljeno v DKUM: 27.10.2015; Ogledov: 2737; Prenosov: 136
.pdf Celotno besedilo (3,70 MB)

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