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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Estudo do fosqueamento de tintas em pó, sistema poliéster/TGIC / Matting study for powder coatings, polyester/TGIC system

Wakim, William 07 July 2017 (has links)
O presente trabalho propôs-se a estudar o fenômeno de fosqueamento em filmes de tinta em pó feitos a partir de resinas poliésteres sólidas pelo sistema conhecido como Triglicidilisocianutato (TGIC). Este fenômeno é indesejado e ocorre na ocasião de mistura de lotes de tintas produzidos independentemente com resinas poliésteres sólidas que compartilham as mesmas fórmulas, especificações e processo industrial. Amostras de uma tríade de resinas poliéster, que apresenta uma particular relação de fosqueamento, foram estudadas por termogravimetria/ termogravimetria derivada (TG/DTG), calorimetria exploratória diferencial (DSC), espectroscopia de ressonância magnética nuclear de Hidrogênio (1H-RMN), cromatografia de permeação em gel (GPC), análise térmica diferencial (DTA) e espectroscopia de infravermelho com transformada de Fourier (FTIR). A partir da análise minuciosa dos resultados obtidos em cada técnica escolhida, não se notou diferenças significativas que pudessem vir a justificar o fosqueamento indesejado para os lotes estudados. Estas avaliações nos permitiram concluir que o fenômeno não ocorre por contaminação industrial dos materiais e que alguma relação latente de fosqueamento por blenda seca deve ainda ser revelada por estudo subsequente. / The present work endeavored to study the matting phenomenon of powder coatings films made of solid polyester resins through a system known as Triglycidyl isocyanurate (TGIC). This phenomenon is an undesired result and occurs when at the time of blending paint batches produced independently with polyester resins that share the same formula, specifications e industrial process. Samples of a polyester resin triad, that shared a particular matting relation, were studied by thermogravimetry/ thermogravimetry derivative (TG/DTG), differential scanning calorimetry nuclear magnetic resonance (1H-NMR), gel permeation chromatog r(aDpShCy), proton (GPC), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). Through in-depth analyses of all results obtained from each chosen method, no accountable differences, that could justify the undesired matting phenomenon, were noticed. These evaluations paved us the way to conclude that the studied phenomenon was not occurring due to industrial contamination, and that some latent dry blend matting relation is still to be revealed by an ensuing study.
252

Fabricação de microcanais por moldagem em poliéster a partir de matriz de silício e pela utilização de toner como resiste para corrosão de vidro / Manufacture microchannel polyester molding from silicon matrix and by the use of toner as resistant to glass corrosion

Silva, Heron Dominguez Torres da 10 August 2001 (has links)
A área de microfabricação de dispositivos de interesse em química analítica tem se expandido muito ao longo dos últimos anos. Uma série de produtos e processos tem sido proposta, tendo como base as tecnologias da área de microeletrônica. Muito destes processos são bastante sofisticados, estando além das necessidades para produção de alguns dispositivos relativamente simples e que são bastante úteis para a química analítica. Este é o caso, por exemplo, dos microcanais para implementação de sistemas eletroforéticos ou micro sistemas em fluxo. Neste contexto, surge a proposta deste trabalho, qual seja desenvolver processos e produtos de interesse nesta área. Esse objetivo foi alcançado pelo desenvolvimento de dois processos: um para produção de microcanais em resina de poliéster através de moldagem e outro de corrosão de vidro utilizando toner de impressora laser como resiste. O primeiro partiu de fotolito para produção de molde em silício através de processo de corrosão por plasma de SF6. Peças de resina de poliéster isoftálica são produzidas por polimerização sobre este molde. Para garantir a desmoldagem não traumática e boa reprodução de detalhes, foi incorporado óleo de silicone durante a preparação da resina. Com este procedimento, foi possível obter canais com 14,0 µm de profundidade e irregularidades superficiais de 1,4 µm para um molde com 15,3 µm de elevação e 0,5 µm de irregularidades superficiais. Com o uso de uma manta flexível de silicone como contraparte, foi possível gerar microcanais cuja altura foi avaliada como sendo da ordem de 5 a 7 µm. Esta avaliação foi conseguida através de medida de condutância após o preenchimento do microcanal com solução de KCl. No segundo processo, toner de impressora laser foi utilizado como resiste para corrosão de vidrO. O layout era diretamente impresso sobre papel aditivado com maltodextrina ou papel utilizado como suporte para etiquetas autocolantes através de uma impressora HP LaserJet 6L com resolução de 600 dpi. Após a transferência térmica da imagem para lâminas de vidro alcalino de 1,0 mm de espessura, a corrosão em ácido fluorídrico permitiu obter canais com 7,1 µm de profundidade e irregularidades de 1,0 µm. Embora este segundo processo apresente desvantagens com relação à resolução tanto no plano da lâmina como na profundidade do canal, quando comparado ao primeiro, deve-se ressaltar a extrema simplicidade, rapidez e baixo custo do processo que deve ser interessante para a produção de protótipos. Já para o primeiro processo, destaca-se a adequação à produção em pequena escala de dispositivos microcanais de baixo custo. / Several processes and products have been proposed to build and use microstructures for chemical purposes. Most of these processes were adapted from microelectronic technologies, which resulted in products with excellent resolution and quality. However, there are some devices that could be generated by simpler and rougher processes. In this work, two processes were developed in order to allow producing simple devices based on microchannels. The first process is a method to produce polyester based devices. A conventional microelectronic process was used to produce a silicon matrix. This matrix was used to produce blocks of isophthalic resin by in situ polymerization. The best results were obtained by adding 1 % (w/w) silicone oil during the polyester resin preparation. This additive improves the mold relief and the smoothness of the device surface. Channels 14.0-µm depth and roughness of 1.4 µm were obtained with a mold with structure height of 15.3 µm and roughness of 0.5 µm. A flexible sheet of silicone allows forming enclosed microchannels with depth of 5-7 µm. This dimension was evaluated by conductance measurement after filling the channel with KCl solution. A process for glass corrosion, using laser printer toner as resist, was proposed. In this method, the layout is printed over a special sheet of paper using a HP LaserJet 6L laser printer. The paper is used to transfer the toner to a soda-lime glass lamina by a thermic process. Hydrofluoric acid solution was used to promote the selective glass corrosion. Channels 7.1-µm depth and roughness of 1.0 µm were obtained. Although this second method does not give the saroe resolution and aspect ratio as the first one, it is suitable to easy and fast prototyping. Gn the other hand, the first method is suitable for low-cost production of devices in small scale.
253

Skidkläders avtagande vattenavvisande effekt : Hur vatten- och oljeavvisande impregneringar påverkas av tvätt, UV-ljus och nötning

INGEMARSSON, MADELENE, SJÖGREN, CHRISTINA January 2013 (has links)
Vatten- och oljeavvisande impregneringar som används i sportartiklar idag består till största del av perfluorerade ämnen, fluorkarboner. Detta har medfört att en stor diskussion kring miljö- och hälsofrågor. Fluorkarboner har egenskapen att vara extremt persistenta och därmed ha en avsaknad av att kunna brytas ned på ett kemiskt eller biologiskt sätt. De är också biackumulerande och toxiska. På grund av fluorkarbonens negativa inverkan har en stor mängd forskning utförts i ett försök till att ersätta dessa ämnen mot mindre miljöfarliga. Skidlärare är en arbetsgrupp som dagligen behöver ett vattenavvisande hjälpmedel i sina arbetskläder, likt impregneringar för att kunna hålla sig varma och torra under arbetspassen i skidbackarna. Företaget F.O.V. Fabrics AB har fått in reklamationer och vidare förfrågningar på de material som de levererar till skidlärares skidkläder, då den vattenavvisande förmågan har börjat avta efter en viss tids användning. En studie har därför gjorts i samarbete med F.O.V. Fabrics AB för att ta reda på om den vattenavvisande effekten försämras på grund av utvalda yttre påfrestningar under användningsfasen. Tre olika vatten- och oljeavvisande impregneringar har använts under den experimentella studien, en innehållande fluorkarboner, en fluorkarbonfri impregnering innehållande dendrimerer och en blandning av dessa två. Vidare har yttre påfrestningar likt tvätt med efterföljande torktumling, UV-ljus och nötning i form av martindale utförts i ett försök till att laborativt simulera skidkläders påfrestningar under användningsfasen. Den potentiellt avtagande vatten- och oljeavvisande effekten kommer att undersökas genom karakteriseringsmetoderna: spray-, bundesmann- och oljetest. Studien har visat att de ingående yttre påfrestningarna som har skett laborativt bidrar till en negativ effekt på samtliga impregneringar. Studien har sammanfattningsvis visat att den vatten- och oljeavvisande effekten inte påverkas nämnvärt efter att ha utsätts för påfrestningar var och en för sig. Det är först vid kombination av två eller fler påfrestningar som den vatten- och oljeavvisande effekten börjat avta. Studien visar också att olika vattenavvisande komponenter försämras efter olika sorters påfrestningar. Fluorkarbonerna har uppvisat en högre känslighet för nötning, vilket kan vara sammankopplat med impregneringens ytstruktur. Den fluorkarbonfria impregneringen har istället visat sig vara känslig för kombinationen av tvätt med efterföljande torktumling och därefter utsättning för UV-ljus. Impregneringen bestående av både fluorkarbon- och fluorkarbonfria vattenavvisande komponenter har visat sig ha en god vattenavvisande effekt genom den experimentella studien. Detta då blandimpregneringen erhåller de positiva effekterna från de skilda vattenavvisande komponenterna vilket i vissa fall har bidragit till en synergistisk effekt. / Program: Textilingenjörsutbildningen
254

Estudo do fosqueamento de tintas em pó, sistema poliéster/TGIC / Matting study for powder coatings, polyester/TGIC system

William Wakim 07 July 2017 (has links)
O presente trabalho propôs-se a estudar o fenômeno de fosqueamento em filmes de tinta em pó feitos a partir de resinas poliésteres sólidas pelo sistema conhecido como Triglicidilisocianutato (TGIC). Este fenômeno é indesejado e ocorre na ocasião de mistura de lotes de tintas produzidos independentemente com resinas poliésteres sólidas que compartilham as mesmas fórmulas, especificações e processo industrial. Amostras de uma tríade de resinas poliéster, que apresenta uma particular relação de fosqueamento, foram estudadas por termogravimetria/ termogravimetria derivada (TG/DTG), calorimetria exploratória diferencial (DSC), espectroscopia de ressonância magnética nuclear de Hidrogênio (1H-RMN), cromatografia de permeação em gel (GPC), análise térmica diferencial (DTA) e espectroscopia de infravermelho com transformada de Fourier (FTIR). A partir da análise minuciosa dos resultados obtidos em cada técnica escolhida, não se notou diferenças significativas que pudessem vir a justificar o fosqueamento indesejado para os lotes estudados. Estas avaliações nos permitiram concluir que o fenômeno não ocorre por contaminação industrial dos materiais e que alguma relação latente de fosqueamento por blenda seca deve ainda ser revelada por estudo subsequente. / The present work endeavored to study the matting phenomenon of powder coatings films made of solid polyester resins through a system known as Triglycidyl isocyanurate (TGIC). This phenomenon is an undesired result and occurs when at the time of blending paint batches produced independently with polyester resins that share the same formula, specifications e industrial process. Samples of a polyester resin triad, that shared a particular matting relation, were studied by thermogravimetry/ thermogravimetry derivative (TG/DTG), differential scanning calorimetry nuclear magnetic resonance (1H-NMR), gel permeation chromatog r(aDpShCy), proton (GPC), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). Through in-depth analyses of all results obtained from each chosen method, no accountable differences, that could justify the undesired matting phenomenon, were noticed. These evaluations paved us the way to conclude that the studied phenomenon was not occurring due to industrial contamination, and that some latent dry blend matting relation is still to be revealed by an ensuing study.
255

Laser textile design : the development of laser dyeing and laser moulding processes to support sustainable design and manufacture

Morgan, Laura January 2016 (has links)
This research developed new creative opportunities for textile design by investigating CO2 laser processing technology to achieve surface design and three-dimensional effects. A practice based and interdisciplinary textile design methodology was employed, integrating scientific and technical approaches with a reflective craft practice. It was found that the synthesis of design and science was imperative to achieving the research goal of evolving techniques that have opened new design opportunities for textile design whilst being viable and communicable for industrial and commercial application. Four distinct Laser Textile Design techniques were developed in this research including: a laser enhanced dyeing technique for wool and wool blends; Peri-Dyeing, a laser dye fixation technique; a laser moulding technique; and a laser fading linen technique.
256

Recombinant Escherichia coli producing an immobilised functional protein at the surface of bio-polyester beads : a novel application for a bio-bead : a thesis presented in partial fulfillment of the requirements of the degree of Master of Science in Microbiology at Massey University, Palmerston North, New Zealand

Atwood, Jane Adair January 2008 (has links)
Polyhydroxyalkanoates (PHAs) are polyesters, produced by many bacteria and some archaea. The most commonly characterised is polyhydroxybutyrate (PHB). Produced when nutrients are growth limiting and carbon available in excess, PHA serves as a carbon-energy storage material and forms generally spherical insoluble inclusions between 50-500nm in diameter in the cytoplasm. The key enzyme for PHA synthesis is the PHA synthase and this enzyme catalyses the polymerisation of (R)-3-hydroxy fatty acids into PHA. PHA synthase remains covalently attached to the growing polyester chain and is displayed on the surface of the PHA granule. Other proteins associated with PHA granules include depolymerases for mobilisation or degradation of granules, regulatory proteins and phasins, proteins that aid in PHA granule stability. PHA bio-beads displaying an IgG binding protein were produced and used to purify IgG from serum demonstrating that the PHA synthase can be engineered to display functional synthase fusion proteins at the PHA granule surface. Correctly folded eukaryotic proteins were also produced and displayed at the PHA granule surface as phasin fusion proteins. Multiple-functionality was also achievable by co-expression of various hybrid genes suggesting that this biotechnological bead production strategy might represent a versatile platform technology. The production of functional eukaryotic proteins at the PHA bead surface represents a novel in vivo matrix-assisted protein folding system. Protein engineering of PHA granule surface proteins provides a novel molecular tool for the display of antigens for FACS based analysis and offers promising possibilities in the development of future biotechnological production processes. Overall, the results obtained in this study strongly enhance the applied potential of these polyester beads in biotechnology and medicine.
257

SYNTHESE ET CARACTERISATION DE NOUVEAUX POLYESTERS BIODEGRADABLES ET HYDROSOLUBLES A FONCTIONS CATIONIQUES OU AMPHOTERES

Nottelet, Benjamin 05 December 2005 (has links) (PDF)
Il n'existe à l'heure actuelle pratiquement pas de copolymères greffés à fonctions cationiques et/ou amphotères présentant une dégradabilité intrinsèque. L'objectif de cette thèse est de générer des composés répondant à ces critères à partir d'une méthode de modification chimique par voie anionique de poly(e-caprolactone) (PCL). A cette fin, deux stratégies principales ont été suivies à partir d'un même intermédiaire réactionnel, un macropolycarbanion dérivé de PCL. La première est fondée sur l'emploi du macropolycabanion en tant qu'agent nucléophile qui réagit avec de petites molécules organiques électrophiles. Ces réactions de substitution ont permis l'obtention de copolymères à base PCL possédant entre 10 et 15% de motifs substitués par des groupes cationiques (ammonium, phosphonium), ou hydrosolubilisants (amine, acide carboxylique). Ces squelettes PCL fonctionnalisés peuvent être utilisés pour effectuer des post-modifications (réactions de couplages, dérivation de fonctions). La seconde stratégie utilise le macropolycarbanion en tant que macroamorceur de polymérisation anionique. Ce type de réaction a été appliqué à des dérivés vinyliques (4-VP, N-VP), des dérivés acryliques (DMAEM, MAPEG), des dérivés acrylamides (DMA, DMAPMA) et des dérivés cycliques (NCA d'acides a-aminés) ce qui a permis d'obtenir des copolymères greffés hydrosolubles à chaîne principale PCL. Ces composés ont des structures partiellement dégradables et forment en solution aqueuse des objets de dimensions nanométriques. Enfin, l'utilisation d'un dérivé polyiodé de PCL en tant que macro-polyagent de transfert est abordée ce qui constitue une nouvelle méthode de polymérisation radicalaire contrôlée par transfert dégénératif d'iode permettant l'obtention de structures greffées.
258

Einfluss der Verzweigung, Terminierung und Immobilisierung auf die Eigenschaften dünner Polyesterschichten / Influence of the branching, termination and immobilisation on the properties of thin polyester films

Reichelt, Senta 25 November 2008 (has links) (PDF)
Die vorliegende Arbeit liefert einen Beitrag zum Verständnis der komplexen Struktur-/Eigenschaftsbeziehungen dünner Schichten hochverzweigter Polyester. Für die umfassende Charakterisierung wurde eine Vielzahl analytischer Methoden kombiniert. Des Weiteren wurde das Anwendungspotential dieser Schichten hinsichtlich möglicher Sensoranwendung anhand der Adsorption von Modellproteinen gewichtet. Dazu war es notwendig verschieden Methoden zur Stabilisierung dieser Schichten zu entwickeln.
259

Wechselwirkung von dünnen Schichten aus HVZ Polyestern im wässrigen Medium mit Modellproteinen

Mikhaylova, Yulia 01 May 2006 (has links) (PDF)
The dissertation work focuses on the whole route of material development starting from the investigations of properties of the initial (raw) HBPs to their applications. Each research step is given in a separate chapter to enhance attention to various aspects of the aim of the work. Thus, every chapter is started with an introduction. After that, the methods applied and experimental procedure are described. Next part tries to give the comprehensive description of the results obtained. At the end of the chapter, the main points are summarized. The Chapter 1 gives the theoretical description of the main experimental techniques used in this work. In Chapter 2 the chemical (chemical composition, purity, typical structure elements) and physical (glass transition temperature, the temperature of the maximum decomposition, the thermal stability at the high temperatures, molar mass, polydispersity and possible aggregation in solution) properties examined by different techniques of polymer analysis are described. The Chapter 3 is divided into three separate parts: In Chapter 3.1 the description of the formation and modification of inter- and intramolecular hydrogen bonds of hydroxyl terminated HBP is presented to reveal the information of hydroxyl groups re- and/or association due to the high temperatures applied. In Chapter 3.2 the nature of the solid-liquid interface of HBP thin films have been studied by different surface sensitive techniques with respect to further protein adsorption investigations. In Chapter 3.3 the strategy for the fabrication of surface attached carboxyl terminated HBP using "grafting to" technique is developed. The Chapter 4 consists of two parts: The first (theoretic) part outlines the basic principles of protein chemistry, factors influencing on the protein molecule stability in aqueous medium, the mechanism of protein adsorption and forces involved in the adsorption process. In the second part the combination of different in situ techniques was applied to obtain a comprehensive description of complex adsorption processes of protein molecules on different polymer surfaces.
260

Design of polyester and porous scaffolds

Odelius, Karin January 2005 (has links)
<p>The use of synthetic materials for tissue and organ reconstruction, i. e. tissue engineering, has become a promising alternative to current surgical therapies and may overcome the shortcomings of the methods in use today. The challenge is in the design and reproducible fabrication of biocompatible and bioresorbable polymers, with suitable surface chemistry, desirable mechanical properties, and the wanted degradation profile. These material properties can be achieved in various manners, including the synthesis of homo- and copolymers along with linear and star-shaped architectures. In many applications the materials’ three-dimensional structure is almost as important as its composition and porous scaffolds with high porosity and interconnected pores that facilitate the in-growth of cells and transportation of nutrients and metabolic waste is desired.</p><p>In this work linear and star-shaped polymers have been synthesized by ring-opening polymerization using a stannous-based catalyst and a spirocyclic tin initiator. A series of linear copolymers with various combinations of 1,5-dioxepane-2-one (DXO), Llactide (LLA) and ε-caprolactone (CL) have been polymerized using stannous octoate as catalyst. It is shown that the composition of the polymers can be chosen in such a manner that the materials’ mechanical and thermal properties can be predetermined. A solvent-casting and particulate leaching scaffold preparation technique has been developed and used to create three-dimensional structures with interconnected pores. The achieved physical properties of these materials’ should facilitate their use in both soft and hard tissue regeneration.</p><p>Well defined star-shaped polyesters have been synthesized using a spirocyclic tin initiator where L-lactide was chosen as a model system for the investigation of the polymerization kinetics. Neither the temperature nor the solvent affects the molecular weight or the molecular weight distribution of the star-shaped polymers, which all show a molecular weight distribution below 1.19 and a molecular weight determined by the initial monomer-to-initiator concentration.</p>

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