Magister Legum - LLM

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No description available.

Ultraviolet-Assisted Direct Ink Write (UV-DIW) is a material extrusion additive manufacturing (AM) technology in which a viscous ink, often at room temperature, is selectively extruded through a translating nozzle to selectively deposit material. The extruded ink is solidified via UV irradiation (photocuring) and three-dimensional parts are created by repeating the process in a layer-by-layer fashion. UV-DIW is an attractive AM technology due to its ability to (1) extrude highly viscous inks (i.e. >10,000 Pa·s if ink exhibits shearthinning behavior) (2) the promise of leveraging the broad photopolymer material library and chemistries established for other AM technologies capable of processing photopolymers and (3) the promise of processing a wide range of inks, which enables the fabrication of metal, ceramic, polymer, bio-based, and multi-material parts. Currently, the technology faces a few shortcomings including (1) limited material selection for UV-DIW due to requirement for inks to be photocurable and limited mechanical properties of photocurable materials (2) lack of feature resolution and topological complexity of printed parts and (3) lack of material screening models providing robust definition of the material requirements (e.g., viscosity, cure time, strength) for successful UV-DIW printing. To address these shortcomings, the goal of this work is to gain a fundamental understanding of the rheological and reactive properties required for successful Ultraviolet-Assisted Direct Ink Write (UV-DIW). The first approach to answering the fundamental research question is establishing the existing rheology experiments used to characterize DIW inks and the relationships between rheology and printability. An in-depth literature review of the techniques and relationships was compiled to better understand ink requirements for successful printing (Chapter 2). This broad survey is not limited to only UV-DIW, but includes all variations of DIW. The first part of the review provides a summary of the rheological experiments that have been used to characterize a wide variety of DIW inks. The second part of this review focuses on the connections between rheology and printability. This survey helps identify the required rheological properties for successful printing that is then used throughout the rest of this work. Additionally, this review identifies shortcomings in current work and proposes areas for future work. From this exhaustive literature review, a systematic roadmap was developed that investigators can follow to quickly characterize the printability of new inks, independent of that ink's specific attributes (Chapter 3). The roadmap simplifies the trends identified in literature into a brief and intuitive guide to the rheology experiments relevant to DIW printing and the relationship between those experiment and printing results. The roadmap was demonstrated by evaluating the printability of two inks: (1) a silicone ink with both yield-stress and reactive curing behavior and (2) urethane acrylate inks with photocuring behavior. Experimental printing studies were used to support the conclusions on printability made in the roadmap. The second main approach focuses on the development of three novel UV-DIW inks to address the current limited material selection for UV-DIW and help better understand the rheological and reactive properties required for successful printing. For the three novel UVDIW inks, the iterative process of ink synthesis, analysis of ink rheology, and printability evaluation was detailed. Data from the development process contributed to gaining a fundamental understanding of how rheology and reactivity affect printability. The three inks each had novel rheological properties that impacted their printing behavior: (1) photocuring (2) yield-stress behavior + photocuring and (3) photocuring + thermal curing. Additionally, each ink had unique properties that expands material selection for UV-DIW including (1) an all-aromatic polyimide possessing a storage modulus above 1 GP a up to 400 °C (Chapter 4), (2) a styrene butadiene rubber (SBR) nanocomposite with elongation at break exceeding 300 % (Chapter 5), and (3) a dual-cure ink enabling the printing of inks containing over 60 vol% highly opaque solids (Chapter 6). The third approach details the development of two UV-DIW process models to better understand the process physics of the UV-DIW process and give insight to the properties of a successful ink. The first process model uses data from photorheology experiments to model how a photocurable ink spreads upon deposition from the nozzle, accounting for transient UV curing behavior (Chapter 7). This model allows for the rapid evaluation of an ink's behavior during the solidification sub-function of UV-DIW solely based on its rheology, without the time-consuming process of trial-and-error printing or complex computer simulations. The second process model combines modeling with a novel experimental method that uses a UV photorheometer to accurately characterize the relationship between cure depth and UV exposure for a wide range of photopolymers (Chapter 8). This model helps understand an inks photocuring behavior and ensure a sufficient cure depth is produced to adhere to the previous layer in UV-DIW printing. Lastly, two UV-DIW process modifications are introduced to address research gaps of printing high resolution features and limited material selection. A hybrid DIW + Vat Photopolymerization system is presented to improve the feature size and topographical complexities of parts, while still retaining UV-DIW's ability to print with very high viscosity photoresins (Chapter 9). A high temperature Heated-DIW system is presented to heat inks to over 300 °C and ultimately enable printing of poly(phenylene sulfide) aerogels (Chapter 10). In enabling the DIW of poly(phenylene sulfide) aerogels, the production of ultra-lightweight thermally insulating components for applications in harsh environments is enabled. With the use of additive manufacturing, hierarchical porosity on the macroscale is enabled in addition to the meso-scale porosity inherent to the aerogels. / Doctor of Philosophy / Direct Ink Write (DIW) is a type of three-dimensional (3D) printing that is used to automatically produce a range of 3D geometries. Specifically, the DIW process selectively extrudes a viscous ink, similar in consistency to peanut butter or toothpaste, through a small moving nozzle to create the features of each layer. This process is like using a frosting bag to decorate a cake with icing. Three-dimensional parts are created by repeating this process and depositing layer on top of layer. While seemingly a straightforward process, it remains relatively unclear what properties an ink needs to produce quality parts. To produce quality parts, the ink first needs to be extruded from the nozzle to form homogenous beads with a constant width and free from breaks. Second, the extruded ink needs to retain the shape that it was deposited in. If the ink spreads excessively, the as-deposited features will be lost and a part resembling a blob will be produced. Lastly, the ink deposited on the first layers needs to have enough strength to support the weight of the part. Otherwise, the part will collapse akin to the Leaning Tower of Pisa. To achieve all three steps and produce a quality part, a successful ink needs to be able to flow through the nozzle and then solidify upon deposition. This work focuses on a specific process called Ultraviolet-Assisted Direct Ink Write (UV-DIW) where materials that solidify when exposed to UV light, called photopolymers, are printed. Currently, the properties of the inks, especially how they cure when exposed to UV light, that produce successful printing remains unclear. This work focuses on understanding how the properties of the photopolymer inks affect the printing behavior of the ink. The ultimate goal of this work is to develop guidelines for the properties of successful inks which will help others develop the next generation of materials printed via UV-DIW. Specifically, experiments are used study how inks behave when they flow through the nozzle (rheology) and then solidify when exposed to UV light (reactivity). This behavior is then connected to the inks printing behavior (printability). In working to better understand the connection between rheology, reactivity, and printability multiple approaches were used. These approaches include the development of new materials for printing via UV-DIW, development of a modified UV-DIW printing process that reduces the size of the printed features, and development of models to predict how inks will behave during printing. The new plastic materials that were developed and successfully printed via UV-DIW have outstanding properties including remaining strong up to 400 °C, being extremely flexible, and a plastic containing a large fraction of a solid filler. With each new material, the formulation was varied to change the inks rheological and reactive properties until successful UV-DIW was enabled. Each new formulation introduced material capabilities not previously available to DIW 3D printing. Then, A modified UV-DIW process was developed that takes advantage of the reactivity of the photopolymers to enable the printing of high-resolution features and shapes not previously possible via DIW 3D printing. In this novel process, a projector is used to project patterned UV light at the material and selectively cure small portions of the deposited material, instead of curing all the deposited material. After printing, the uncured ink is washed away resulting in features much smaller than what can be produced when directly extruding them. Finally, the developed process models use the relatively simple rheology and reactivity experiments, to predict how an ink behaves during the UV-DIW process. Using the results of these experiments and the developed models, the inks behavior during the printing process is predicted. These models allow for the properties of new inks to be quickly measured and their printing behavior predicted. New ink formulations can be quickly screened, and optimal process parameters predicted. Overall, this work produces guidelines for the rheological and reactive properties required of a photopolymer ink to produce successful UV-DIW printing. Future researchers can use these guidelines to develop the next generation of materials printed via UV-DIW more easily.

published_or_final_version / Fine Arts / Master / Master of Philosophy

Os dispositivos emissores de luz orgânicos OLEDs têm despertado um enorme interesse tanto da comunidade científica quanto das empresas presentes no mercado mundial de displays. As características de elevado ângulo de visão, alta eficiência energética, possibilidade de confecção de displays flexíveis que não necessitam retroiluminação, baixo peso, fácil processabilidade, dentre outras, fazem com que os displays fabricados com materiais orgânicos apresentem um enorme potencial para as mais diversas aplicações. O presente trabalho teve como objetivo contribuir para a construção e caracterização de displays monocromáticos à base de polímeros luminescentes depositados pela técnica Ink Jet. Para tanto foram preparados os padrões de linhas x colunas, formadores dos pontos luminosos (pixels) de matrizes passivas e desenvolvidos processos para deposição dos filmes finos de polímeros semicondutores. A utilização da deposição por Ink Jet aparece como uma técnica chave para a produção de dispositivos poliméricos. Nesta pesquisa, como material luminescente foi utilizado um polímero da família do polifluoreno, de fácil processamento e elevada eficiência luminosa, enquanto que como eletrodos foram utilizados o óxido de estanho e índio (ITO) e Alumínio. O ITO foi utilizado por possuir baixa resistividade elétrica, elevada função de trabalho e elevada transmitância na região do visível. O processo de encapsulamento do display se deu por meio do acondicionamento destes dispositivos em ambiente isento de oxigênio e umidade, evitando-se os efeitos já conhecidos da foto-oxidação das camadas poliméricas. Os dispositivos, uma vez preparados, foram caracterizados por meio de medidas ópticas (fotoluminescência), elétricas (eletroluminescência, condutividade) e de desempenho (eficiência luminosa e luminância). / Organic Light Emitters Diodes OLEDs is a promising field of study and a huge market opportunity to semiconductor players. Thanks to its potential characteristics to replace the main todays display technologies like lightweight, low voltage, wide viewing angle, high resolution, fast switching, broad color range and the possibility to fabricate flexible devices, makes the organic semiconductors a potential candidate to develop, in a near future, devices and systems that even could not be imagined before. This work aims to contribute to the manufacturing process field and to the characterization of displays made by ink jet deposition technique. To achieve this objective, line x column patterns were produced, in which the pixels are generated at the crossing of lines and columns. The ink jet printing of materials is playing an important role in industry because it provides a low-cost manufacture environment potential. In this work, we studied the morphology of the ink jet deposition of polyfluorene over Indium Tin Oxide (ITO) substrates treated by different procedures. Those materials where used because the polyfluorene polymer presents high light emission efficiency and easiness of processing. The electrodes were prepared with ITO (due its low resistivity, high work function and high transmittance in the visible spectrum) and aluminum. The processed displays were sealed inside an inert ambient with positive pressure to avoid the photo-oxidation of the semiconductor luminescent polymer layers. The devices were characterized by optical (photoluminescence), electrical (electroluminescence) and performance (brightness, luminous efficiency) measurements.

Os dispositivos emissores de luz orgânicos OLEDs têm despertado um enorme interesse tanto da comunidade científica quanto das empresas presentes no mercado mundial de displays. As características de elevado ângulo de visão, alta eficiência energética, possibilidade de confecção de displays flexíveis que não necessitam retroiluminação, baixo peso, fácil processabilidade, dentre outras, fazem com que os displays fabricados com materiais orgânicos apresentem um enorme potencial para as mais diversas aplicações. O presente trabalho teve como objetivo contribuir para a construção e caracterização de displays monocromáticos à base de polímeros luminescentes depositados pela técnica Ink Jet. Para tanto foram preparados os padrões de linhas x colunas, formadores dos pontos luminosos (pixels) de matrizes passivas e desenvolvidos processos para deposição dos filmes finos de polímeros semicondutores. A utilização da deposição por Ink Jet aparece como uma técnica chave para a produção de dispositivos poliméricos. Nesta pesquisa, como material luminescente foi utilizado um polímero da família do polifluoreno, de fácil processamento e elevada eficiência luminosa, enquanto que como eletrodos foram utilizados o óxido de estanho e índio (ITO) e Alumínio. O ITO foi utilizado por possuir baixa resistividade elétrica, elevada função de trabalho e elevada transmitância na região do visível. O processo de encapsulamento do display se deu por meio do acondicionamento destes dispositivos em ambiente isento de oxigênio e umidade, evitando-se os efeitos já conhecidos da foto-oxidação das camadas poliméricas. Os dispositivos, uma vez preparados, foram caracterizados por meio de medidas ópticas (fotoluminescência), elétricas (eletroluminescência, condutividade) e de desempenho (eficiência luminosa e luminância). / Organic Light Emitters Diodes OLEDs is a promising field of study and a huge market opportunity to semiconductor players. Thanks to its potential characteristics to replace the main todays display technologies like lightweight, low voltage, wide viewing angle, high resolution, fast switching, broad color range and the possibility to fabricate flexible devices, makes the organic semiconductors a potential candidate to develop, in a near future, devices and systems that even could not be imagined before. This work aims to contribute to the manufacturing process field and to the characterization of displays made by ink jet deposition technique. To achieve this objective, line x column patterns were produced, in which the pixels are generated at the crossing of lines and columns. The ink jet printing of materials is playing an important role in industry because it provides a low-cost manufacture environment potential. In this work, we studied the morphology of the ink jet deposition of polyfluorene over Indium Tin Oxide (ITO) substrates treated by different procedures. Those materials where used because the polyfluorene polymer presents high light emission efficiency and easiness of processing. The electrodes were prepared with ITO (due its low resistivity, high work function and high transmittance in the visible spectrum) and aluminum. The processed displays were sealed inside an inert ambient with positive pressure to avoid the photo-oxidation of the semiconductor luminescent polymer layers. The devices were characterized by optical (photoluminescence), electrical (electroluminescence) and performance (brightness, luminous efficiency) measurements.

<p> Denna uppsats undersöker vilket kulturell roll tatueringarna har haft historiskt genom en litteraturstudie.</p><p> Tatueringskonsten har praktiserats av människor världen över i tusentals år och man har funnit bevis på att man använde sig av tatueringar i antika Grekland och Romarriket. Många kulturer har av olika anledningar använt sig av tatueringar och gett tatuering en stor social och kulturell mening. Tatueringar har använts för att markera brottslingar, slavar och andra stigmatiserade grupper men har också varit en statussymbol och en identitetsmarkör. Kan man se likheter i hur tatueringar blivit framställda i litteraturen trots skillnader i både tid och rum hos de som utövat tatueringskonsten?</p><p> Uppsatsen undersöker även hur tatueringar framställs inom populärkulturen idag genom att analysera två realitytv-serier; Miami Ink och LA Ink. Uppsatsen ämnar utreda om hur tatueringar framställts under historiens gång även kan ses i hur de framställs i populärkulturen idag. Genom att titta på hur tatueringar, tatuerare och de som tatuerar sig porträtteras i populärkulturen ämnar uppsatsen utröna hur man ser på tatueringar idag.</p> / <p><em> Tattoos over time and continents – as art, stigma and identity</em> explores by a litterature study  the cultural significance of tattoos’s throughout history.</p><p> Tattooing has been practiced by mankind all over the world for thousands of years and evidence also suggests that tattooing was practiced in ancient Greece and in Rome. Many different cultures have used tattooing for a wide variety of reasons and given the tattoos their great cultural and social meaning. Tattoos have been used to mark prisoners, slaves and other stigmatisiced groups, but also as a sign of status and a mark of identity and heritage. Is it possible to find similarities in different tattoocultures, presented in literature, despite differences in both time and place?</p><p> This thesis also explores how tattoos are presented in the field of popular culture today by analyzing two reality-shows: Miami Ink and LA Ink.  The thesis seeks to investigate if some of the ways tattoos have been presented in history can be seen in the way they are presented in popular culture today. The thesis analyses how the tattoos, the tattoo artists and their clients are portrayed in popular culture in order to investigate how tattoos are seen today.  <strong></strong></p>

Denna uppsats undersöker vilket kulturell roll tatueringarna har haft historiskt genom en litteraturstudie.  Tatueringskonsten har praktiserats av människor världen över i tusentals år och man har funnit bevis på att man använde sig av tatueringar i antika Grekland och Romarriket. Många kulturer har av olika anledningar använt sig av tatueringar och gett tatuering en stor social och kulturell mening. Tatueringar har använts för att markera brottslingar, slavar och andra stigmatiserade grupper men har också varit en statussymbol och en identitetsmarkör. Kan man se likheter i hur tatueringar blivit framställda i litteraturen trots skillnader i både tid och rum hos de som utövat tatueringskonsten?  Uppsatsen undersöker även hur tatueringar framställs inom populärkulturen idag genom att analysera två realitytv-serier; Miami Ink och LA Ink. Uppsatsen ämnar utreda om hur tatueringar framställts under historiens gång även kan ses i hur de framställs i populärkulturen idag. Genom att titta på hur tatueringar, tatuerare och de som tatuerar sig porträtteras i populärkulturen ämnar uppsatsen utröna hur man ser på tatueringar idag. / Tattoos over time and continents – as art, stigma and identity explores by a litterature study  the cultural significance of tattoos’s throughout history.  Tattooing has been practiced by mankind all over the world for thousands of years and evidence also suggests that tattooing was practiced in ancient Greece and in Rome. Many different cultures have used tattooing for a wide variety of reasons and given the tattoos their great cultural and social meaning. Tattoos have been used to mark prisoners, slaves and other stigmatisiced groups, but also as a sign of status and a mark of identity and heritage. Is it possible to find similarities in different tattoocultures, presented in literature, despite differences in both time and place?  This thesis also explores how tattoos are presented in the field of popular culture today by analyzing two reality-shows: Miami Ink and LA Ink.  The thesis seeks to investigate if some of the ways tattoos have been presented in history can be seen in the way they are presented in popular culture today. The thesis analyses how the tattoos, the tattoo artists and their clients are portrayed in popular culture in order to investigate how tattoos are seen today.

published_or_final_version / Humanities / Doctoral / Doctor of Philosophy